30f96dfee1868d8b2c9a5196590c9021fd0182c1
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67\usepackage{harpoon}%
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69\usepackage{fancyhdr}
70
71\title{Year 12 Specialist}
72\author{Andrew Lorimer}
73\date{2019}
74
75\begin{document}
76
77\pagestyle{fancy}
78\fancyhead[LO,LE]{Year 12 Specialist}
79\fancyhead[CO,CE]{Andrew Lorimmer}
80\maketitle
81
82\section{Complex \& Imaginary Numbers}\label{complex-imaginary-numbers}
83
84\subsection{Imaginary numbers}\label{imaginary-numbers}
85
86\[i^2 = -1 \quad \therefore i = \sqrt {-1}\]
87
88\subsubsection{Simplifying negative
89surds}\label{simplifying-negative-surds}
90
91\begin{equation}\begin{split}\sqrt{-2} & = \sqrt{-1 \times 2} \\ & = \sqrt{2}i\end{split}\end{equation}
92
93\subsection{Complex numbers}\label{complex-numbers}
94
95\[\mathbb{C} = \{a+bi : a, b \in \mathbb{R} \}\]
96
97General form: \(z=a+bi\)\\
98\(\operatorname{Re}(z) = a, \quad \operatorname{Im}(z) = b\)
99
100\subsubsection{Addition}\label{addition}
101
102If \(z_1 = a+bi\) and \(z_2=c+di\), then
103
104\[z_1+z_2 = (a+c)+(b+d)i\]
105
106\subsubsection{Subtraction}\label{subtraction}
107
108If \(z_1=a+bi\) and \(z_2=c+di\), then
109
110\[z_1 - z_2=(a−c)+(b−d)i\]
111
112\subsubsection{Multiplication by a real
113constant}\label{multiplication-by-a-real-constant}
114
115If \(z=a+bi\) and \(k \in \mathbb{R}\), then
116
117\[kz=ka+kbi\]
118
119\subsubsection{\texorpdfstring{Powers of
120\(i\)}{Powers of i}}\label{powers-of-i}
121
122\begin{itemize}
123\tightlist
124\item
125 \(i^{4n} = 1\)
126\item
127 \(i^{4n+1} = i\)
128\item
129 \(i^{4n+2} = -1\)
130\item
131 \(i^{4n+3} = -i\)
132\end{itemize}
133
134For \(i^n\), find remainder \(r\) when \(n \div 4\). Then \(i^n = i^r\).
135
136\subsubsection{Multiplying complex
137expressions}\label{multiplying-complex-expressions}
138
139If \(z_1 = a+bi\) and \(z_2=c+di\), then
140
141\[z_1 \times z_2 = (ac-bd)+(ad+bc)i\]
142
143\subsubsection{Conjugates}\label{conjugates}
144
145\[\overline{z} = a \mp bi\]
146
147\subparagraph{Properties}\label{properties}
148
149\begin{itemize}
150\tightlist
151\item
152 \(\overline{z_1 + z_2} = \overline{z_1} + \overline{z_2}\)
153\item
154 \(\overline{z_1 z_2} = \overline{z_1} \cdot \overline{z_2}\)
155\item
156 \(\overline{kz} = k \overline{z}, \text{ for } k \in \mathbb{R}\)
157\item
158 \(z \overline{z} = = (a+bi)(a-bi) = a^2+b^2 = |z|^2\)
159\item
160 \(z + \overline{z} = 2 \operatorname{Re}(z)\)
161\end{itemize}
162
163\subsubsection{Modulus}\label{modulus}
164
165Distance from origin.
166
167\[|{z}|=\sqrt{a^2+b^2} \quad \therefore z \overline{z} = |z|^2\]
168
169Properties
170
171\begin{itemize}
172\tightlist
173\item
174 \(|z_1 z_2| = |z_1| |z_2|\)
175\item
176 \(|{z_1 \over z_2}| = {|z_1| \over |z_2|}\)
177\item
178 \(|z_1 + z_2| \le |z_1 + |z_2|\)
179\end{itemize}
180
181\subsubsection{Multiplicative inverse}\label{multiplicative-inverse}
182
183\begin{equation}\begin{split}z^{-1} & = {1 \over z} \\ & = {{a-bi} \over {a^2+B^2}} \\ & = {\overline{z} \over {|z|^2}}\end{split}\end{equation}
184
185\subsubsection{Dividing complex numbers}\label{dividing-complex-numbers}
186
187\[{{z_1} \over {z_2}} = {{z_1\ {z_2}^{-1}}} = {{z_1 \overline{z_2}} \over {{|z_2|}^2}} \quad \text{(multiplicative inverse)}\]
188
189In practice, rationalise denominator:
190
191\[{z_1 \over z_2} = {{(a+bi)(c-di)} \over {c^2+d^2}}\]
192
193\subsection{Argand planes}\label{argand-planes}
194
195\begin{itemize}
196\tightlist
197\item
198 Geometric representation of \(\mathbb{C}\)
199\item
200 horizontal \(= \operatorname{Re}(z)\); vertical
201 \(= \operatorname{Im}(z)\)
202\item
203 Multiplication by \(i\) results in an anticlockwise rotation of
204 \(\pi \over 2\)
205\end{itemize}
206
207\vfil \break
208
209\subsection{Complex polynomials}\label{complex-polynomials}
210
211\textbf{Include \(\pm\) for all solutions, including imaginary}
212
213\subsubsection{Sum of two squares
214(quadratics)}\label{sum-of-two-squares-quadratics}
215
216\[z^2+a^2=z^2-(ai)^2=(z+ai)(z-ai)\]
217
218Complete the square to get to this point.
219
220\paragraph{Dividing complex
221polynomials}\label{dividing-complex-polynomials}
222
223\(P(z) \div D(z)\) gives quotient \(Q(z)\) and remainder \(R(z)\):
224
225\[P(z) = D(z)Q(z) + R(z)\]
226
227\paragraph{Remainder theorem}\label{remainder-theorem}
228
229Let \(\alpha \in \mathbb{C}\). Remainder of \(P(z) \div (z - \alpha)\)
230is \(P(\alpha)\)
231
232\paragraph{Factor theorem}\label{factor-theorem}
233
234If \(a+bi\) is a solution to \(P(z)=0\), then:
235
236\begin{itemize}
237\tightlist
238\item
239 \(P(a+bi)=0\)
240\item
241 \(z-(a+bi)\) is a factor of \(P(z)\)
242\end{itemize}
243
244\paragraph{Sum of two cubes}\label{sum-of-two-cubes}
245
246\[a^3 \pm b^3 = (a \pm b)(a^2 \mp ab + b^2)\]
247
248\subsection{Conjugate root theorem}\label{conjugate-root-theorem}
249
250If \(a+bi\) is a solution to \(P(z)=0\), then the conjugate
251\(\overline{z}=a-bi\) is also a solution.
252
253\subsection{Polar form}\label{polar-form}
254
255\begin{equation}\begin{split}z & =r \operatorname{cis} \theta \\ & = r(\operatorname{cos}\theta+i \operatorname{sin}\theta) \\ & = a + bi \end{split}\end{equation}
256
257\begin{itemize}
258\tightlist
259\item
260 \(r=|z|=\sqrt{\operatorname{Re}(z)^2 + \operatorname{Im}(z)^2}\)
261\item
262 \(\theta=\operatorname{arg}(z)\) (on CAS: \texttt{arg(a+bi)})
263\item
264 \textbf{principal argument} is
265 \(\operatorname{Arg}(z) \in (-\pi, \pi]\) (note capital
266 \(\operatorname{Arg}\))
267\end{itemize}
268
269Each complex number has multiple polar representations:\\
270\(z=r \operatorname{cis} \theta = r \operatorname{cis} (\theta+2 n\pi\))
271with \(n \in \mathbb{Z}\) revolutions
272
273\subsubsection{Conjugate in polar form}\label{conjugate-in-polar-form}
274
275\[(r \operatorname{cis} \theta)^{-1} = r\operatorname{cis} (- \theta)\]
276
277Reflection of \(z\) across horizontal axis.
278
279\subsubsection{Multiplication and division in polar
280form}\label{multiplication-and-division-in-polar-form}
281
282\[z_1z_2=r_1r_2\operatorname{cis}(\theta_1+\theta_2)\]
283
284\[{z_1 \over z_2} = {r_1 \over r_2} \operatorname{cis}(\theta_1-\theta_2)\]
285
286\subsection{de Moivres' Theorem}\label{de-moivres-theorem}
287
288\[(r\operatorname{cis}\theta)^n=r^n\operatorname{cis}(n\theta) \text{ where } n \in \mathbb{Z}\]
289
290\subsection{Roots of complex numbers}\label{roots-of-complex-numbers}
291
292\(n\)th roots of \(z = r \operatorname{cis} \theta\) are
293
294\[z={r^{1 \over n}} \operatorname{cis}({{\theta + 2 k \pi} \over n})\]
295
296Same modulus for all solutions. Arguments are separated by
297\({2 \pi} \over n\)
298
299The solutions of \(z^n=a \text{ where } a \in \mathbb{C}\) lie on circle
300
301\[x^2 + y^2 = (|a|^{1 \over n})^2\]
302
303\subsection{Sketching complex graphs}\label{sketching-complex-graphs}
304
305\subsubsection{Straight line}\label{straight-line}
306
307\begin{itemize}
308\tightlist
309\item
310 \(\operatorname{Re}(z) = c\) or \(\operatorname{Im}(z) = c\)
311 (perpendicular bisector)
312\item
313 \(\operatorname{Arg}(z) = \theta\)
314\item
315 \(|z+a|=|z+bi|\) where \(m={a \over b}\)
316\item
317 \(|z+a|=|z+b| \longrightarrow 2(a-b)x=b^2-a^2\)
318\end{itemize}
319
320\subsubsection{Circle}\label{circle}
321
322\(|z-z_1|^2 = c^2 |z_2+2|^2\) or \(|z-(a + bi)| = c\)
323
324\subsubsection{Locus}\label{locus}
325
326\(\operatorname{Arg}(z) < \theta\)
327
328\section{Vectors}\label{vectors}
329
330\begin{itemize}
331\tightlist
332\item
333 \textbf{vector:} a directed line segment\\
334\item
335 arrow indicates direction
336\item
337 length indicates magnitude
338\item
339 column notation: \(\begin{bmatrix} x \\ y \end{bmatrix}\)
340\item
341 vectors with equal magnitude and direction are equivalent
342\end{itemize}
343
344\begin{figure}
345\centering
346\includegraphics[width=0.20000\textwidth]{graphics/vectors-intro.png}
347\caption{}\label{id}
348\end{figure}
349
350\subsection{Vector addition}\label{vector-addition}
351
352\(\boldsymbol{u} + \boldsymbol{v}\) can be represented by drawing each
353vector head to tail then joining the lines.\\
354Addition is commutative (parallelogram)
355
356\subsection{Scalar multiplication}\label{scalar-multiplication}
357
358For \(k \in \mathbb{R}^+\), \(k\boldsymbol{u}\) has the same direction
359as \(\boldsymbol{u}\) but length is multiplied by a factor of \(k\).
360
361When multiplied by \(k < 0\), direction is reversed and length is
362multplied by \(k\).
363
364\subsection{Vector subtraction}\label{vector-subtraction}
365
366To find \(\boldsymbol{u} - \boldsymbol{v}\), add \(\boldsymbol{-v}\) to
367\(\boldsymbol{u}\)
368
369\subsection{Parallel vectors}\label{parallel-vectors}
370
371Same or opposite direction
372
373\[\boldsymbol{u} || \boldsymbol{v} \iff \boldsymbol{u} = k \boldsymbol{v} \text{ where } k \in \mathbb{R} \setminus \{0\}\]
374
375\subsection{Position vectors}\label{position-vectors}
376
377Vectors may describe a position relative to \(O\).
378
379For a point \(A\), the position vector is \overrightharp{OA}
380
381\vfill\eject
382
383\subsection{Linear combinations of non-parallel
384vectors}\label{linear-combinations-of-non-parallel-vectors}
385
386If two non-zero vectors \(\boldsymbol{a}\) and \(\boldsymbol{b}\) are
387not parallel, then:
388
389\[m\boldsymbol{a} + n\boldsymbol{b} = p \boldsymbol{a} + q \boldsymbol{b}\quad \therefore \quad m = p, \> n = q\]
390
391\includegraphics[width=0.20000\textwidth]{graphics/parallelogram-vectors.jpg}
392\includegraphics[width=0.10000\textwidth]{graphics/vector-subtraction.jpg}
393
394\subsection{Column vector notation}\label{column-vector-notation}
395
396A vector between points \(A(x_1,y_1), \> B(x_2,y_2)\) can be represented
397as \(\begin{bmatrix}x_2-x_1\\ y_2-y_1 \end{bmatrix}\)
398
399\subsection{Component notation}\label{component-notation}
400
401A vector \(\boldsymbol{u} = \begin{bmatrix}x\\ y \end{bmatrix}\) can be
402written as \(\boldsymbol{u} = x\boldsymbol{i} + y\boldsymbol{j}\).\\
403\(\boldsymbol{u}\) is the sum of two components \(x\boldsymbol{i}\) and
404\(y\boldsymbol{j}\)\\
405Magnitude of vector
406\(\boldsymbol{u} = x\boldsymbol{i} + y\boldsymbol{j}\) is denoted by
407\(|u|=\sqrt{x^2+y^2}\)
408
409Basic algebra applies:\\
410\((x\boldsymbol{i} + y\boldsymbol{j}) + (m\boldsymbol{i} + n\boldsymbol{j}) = (x + m)\boldsymbol{i} + (y+n)\boldsymbol{j}\)\\
411Two vectors equal if and only if their components are equal.
412
413\subsection{\texorpdfstring{Unit vector
414\(|\hat{\boldsymbol{a}}|=1\)}{Unit vector \textbar{}\textbackslash{}hat\{\textbackslash{}boldsymbol\{a\}\}\textbar{}=1}}\label{unit-vector-hatboldsymbola1}
415
416\begin{equation}\begin{split}\hat{\boldsymbol{a}} & = {1 \over {|\boldsymbol{a}|}}\boldsymbol{a} \\ & = \boldsymbol{a} \cdot {|\boldsymbol{a}|}\end{split}\end{equation}
417
418\subsection{\texorpdfstring{Scalar/dot product
419\(\boldsymbol{a} \cdot \boldsymbol{b}\)}{Scalar/dot product \textbackslash{}boldsymbol\{a\} \textbackslash{}cdot \textbackslash{}boldsymbol\{b\}}}\label{scalardot-product-boldsymbola-cdot-boldsymbolb}
420
421\[\boldsymbol{a} \cdot \boldsymbol{b} = a_1 b_1 + a_2 b_2\]
422
423\textbf{on CAS:} \texttt{dotP({[}a\ b\ c{]},\ {[}d\ e\ f{]})}
424
425\subsection{Scalar product properties}\label{scalar-product-properties}
426
427\begin{enumerate}
428\def\labelenumi{\arabic{enumi}.}
429\tightlist
430\item
431 \(k(\boldsymbol{a\cdot b})=(k\boldsymbol{a})\cdot \boldsymbol{b}=\boldsymbol{a}\cdot (k{b})\)
432\item
433 \(\boldsymbol{a \cdot 0}=0\)
434\item
435 \(\boldsymbol{a \cdot (b + c)}=\boldsymbol{a \cdot b + a \cdot c}\)
436\item
437 \(\boldsymbol{i \cdot i} = \boldsymbol{j \cdot j} = \boldsymbol{k \cdot k}= 1\)
438\item
439 If \(\boldsymbol{a} \cdot \boldsymbol{b} = 0\), \(\boldsymbol{a}\) and
440 \(\boldsymbol{b}\) are perpendicular
441\item
442 \(\boldsymbol{a \cdot a} = |\boldsymbol{a}|^2 = a^2\)
443\end{enumerate}
444
445For parallel vectors \(\boldsymbol{a}\) and \(\boldsymbol{b}\):\\
446\[\boldsymbol{a \cdot b}=\begin{cases}
447|\boldsymbol{a}||\boldsymbol{b}| \hspace{2.8em} \text{if same direction}\\
448-|\boldsymbol{a}||\boldsymbol{b}| \hspace{2em} \text{if opposite directions}
449\end{cases}\]
450
451\subsection{Geometric scalar products}\label{geometric-scalar-products}
452
453\[\boldsymbol{a} \cdot \boldsymbol{b} = |\boldsymbol{a}| |\boldsymbol{b}| \cos \theta\]
454
455where \(0 \le \theta \le \pi\)
456
457\subsection{Perpendicular vectors}\label{perpendicular-vectors}
458
459If \(\boldsymbol{a} \cdot \boldsymbol{b} = 0\), then
460\(\boldsymbol{a} \perp \boldsymbol{b}\) (since \(\cos 90 = 0\))
461
462\subsection{Finding angle between
463vectors}\label{finding-angle-between-vectors}
464
465\textbf{positive direction}
466
467\[\cos \theta = {{\boldsymbol{a} \cdot \boldsymbol{b}} \over {|\boldsymbol{a}| |\boldsymbol{b}|}} = {{a_1 b_1 + a_2 b_2} \over {|\boldsymbol{a}| |\boldsymbol{b}|}}\]
468
469\textbf{on CAS:} \texttt{angle({[}a\ b\ c{]},\ {[}a\ b\ c{]})} (Action
470-\textgreater{} Vector -\textgreater{} Angle)
471
472\subsection{Angle between vector and
473axis}\label{angle-between-vector-and-axis}
474
475Direction of a vector can be given by the angles it makes with
476\(\boldsymbol{i}, \boldsymbol{j}, \boldsymbol{k}\) directions.
477
478For
479\(\boldsymbol{a} = a_1 \boldsymbol{i} + a_2 \boldsymbol{j} + a_3 \boldsymbol{k}\)
480which makes angles \(\alpha, \beta, \gamma\) with positive direction of
481\(x, y, z\) axes:
482\[\cos \alpha = {a_1 \over |\boldsymbol{a}|}, \quad \cos \beta = {a_2 \over |\boldsymbol{a}|}, \quad \cos \gamma = {a_3 \over |\boldsymbol{a}|}\]
483
484\textbf{on CAS:} \texttt{angle({[}a\ b\ c{]},\ {[}1\ 0\ 0{]})} for angle
485between \(a\boldsymbol{i} + b\boldsymbol{j} + c\boldsymbol{k}\) and
486\(x\)-axis
487
488\subsection{Vector projections}\label{vector-projections}
489
490Vector resolute of \(\boldsymbol{a}\) in direction of \(\boldsymbol{b}\)
491is magnitude of \(\boldsymbol{a}\) in direction of \(\boldsymbol{b}\):
492
493\[\boldsymbol{u}={{\boldsymbol{a}\cdot\boldsymbol{b}}\over |\boldsymbol{b}|^2}\boldsymbol{b}=\left({\boldsymbol{a}\cdot{\boldsymbol{b} \over |\boldsymbol{b}|}}\right)\left({\boldsymbol{b} \over |\boldsymbol{b}|}\right)=(\boldsymbol{a} \cdot \hat{\boldsymbol{b}})\hat{\boldsymbol{b}}\]
494
495\subsection{\texorpdfstring{Scalar resolute of \(\boldsymbol{a}\) on
496\(\boldsymbol{b}\)}{Scalar resolute of \textbackslash{}boldsymbol\{a\} on \textbackslash{}boldsymbol\{b\}}}\label{scalar-resolute-of-boldsymbola-on-boldsymbolb}
497
498\[r_s = |\boldsymbol{u}| = \boldsymbol{a} \cdot \hat{\boldsymbol{b}}\]
499
500\subsection{\texorpdfstring{Vector resolute of
501\(\boldsymbol{a} \perp \boldsymbol{b}\)}{Vector resolute of \textbackslash{}boldsymbol\{a\} \textbackslash{}perp \textbackslash{}boldsymbol\{b\}}}\label{vector-resolute-of-boldsymbola-perp-boldsymbolb}
502
503\[\boldsymbol{w} = \boldsymbol{a} - \boldsymbol{u} \> \text{ where } \boldsymbol{u} \text{ is projection } \boldsymbol{a} \text{ on } \boldsymbol{b}\]
504
505\subsection{Vector proofs}\label{vector-proofs}
506
507\subsubsection{Concurrent lines}\label{concurrent-lines}
508
509\(\ge\) 3 lines intersect at a single point
510
511\subsubsection{Collinear points}\label{collinear-points}
512
513\(\ge\) 3 points lie on the same line\\
514\(\implies \vec{OC} = \lambda \vec{OA} + \mu \vec{OB}\) where
515\(\lambda + \mu = 1\). If \(C\) is between \(\vec{AB}\), then
516\(0 < \mu < 1\)\\
517Points \(A, B, C\) are collinear iff
518\(\vec{AC}=m\vec{AB} \text{ where } m \ne 0\)
519
520\subsubsection{Useful vector properties}\label{useful-vector-properties}
521
522\begin{itemize}
523\tightlist
524\item
525 If \(\boldsymbol{a}\) and \(\boldsymbol{b}\) are parallel, then
526 \(\boldsymbol{b}=k\boldsymbol{a}\) for some
527 \(k \in \mathbb{R} \setminus \{0\}\)
528\item
529 If \(\boldsymbol{a}\) and \(\boldsymbol{b}\) are parallel with at
530 least one point in common, then they lie on the same straight line
531\item
532 Two vectors \(\boldsymbol{a}\) and \(\boldsymbol{b}\) are
533 perpendicular if \(\boldsymbol{a} \cdot \boldsymbol{b}=0\)
534\item
535 \(\boldsymbol{a} \cdot \boldsymbol{a} = |\boldsymbol{a}|^2\)
536\end{itemize}
537
538\subsection{Linear dependence}\label{linear-dependence}
539
540Vectors \(\boldsymbol{a}, \boldsymbol{b}, \boldsymbol{c}\) are linearly
541dependent if they are non-parallel and:
542
543\[k\boldsymbol{a}+l\boldsymbol{b}+m\boldsymbol{c} = 0\]
544\[\therefore \boldsymbol{c} = m\boldsymbol{a} + n\boldsymbol{b} \quad \text{(simultaneous)}\]
545
546\(\boldsymbol{a}, \boldsymbol{b},\) and \(\boldsymbol{c}\) are linearly
547independent if no vector in the set is expressible as a linear
548combination of other vectors in set, or if they are parallel.
549
550Vector \(\boldsymbol{w}\) is a linear combination of vectors
551\(\boldsymbol{v_1}, \boldsymbol{v_2}, \boldsymbol{v_3}\)
552
553\subsection{Three-dimensional vectors}\label{three-dimensional-vectors}
554
555Right-hand rule for axes: \(z\) is up or out of page.
556
557i\includegraphics{graphics/vectors-3d.png}
558
559\subsection{Parametric vectors}\label{parametric-vectors}
560
561Parametric equation of line through point \((x_0, y_0, z_0)\) and
562parallel to \(a\boldsymbol{i} + b\boldsymbol{j} + c\boldsymbol{k}\) is:
563
564\begin{equation}\begin{cases}x = x_o + a \cdot t \\ y = y_0 + b \cdot t \\ z = z_0 + c \cdot t\end{cases}\end{equation}
565
566\section{Circular functions}\label{circular-functions}
567
568Period of \(a\sin(bx)\) is \({2\pi} \over b\)
569
570Period of \(a\tan(nx)\) is \(\pi \over n\)\\
571Asymptotes at \(x={2k+1)\pi \over 2n} \> \vert \> k \in \mathbb{Z}\)
572
573\subsection{Reciprocal functions}\label{reciprocal-functions}
574
575\subsubsection{Cosecant}\label{cosecant}
576
577\begin{figure}
578\centering
579\includegraphics{graphics/csc.png}
580\caption{}
581\end{figure}
582
583\[\operatorname{cosec} \theta = {1 \over \sin \theta} \> \vert \> \sin \theta \ne 0\]
584
585\begin{itemize}
586\tightlist
587\item
588 \textbf{Domain} \(= \mathbb{R} \setminus {n\pi : n \in \mathbb{Z}}\)
589\item
590 \textbf{Range} \(= \mathbb{R} \setminus (-1, 1)\)
591\item
592 \textbf{Turning points} at
593 \(\theta = {{(2n + 1)\pi} \over 2} \> \vert \> n \in \mathbb{Z}\)
594\item
595 \textbf{Asymptotes} at \(\theta = n\pi \> \vert \> n \in \mathbb{Z}\)
596\end{itemize}
597
598\subsubsection{Secant}\label{secant}
599
600\begin{figure}
601\centering
602\includegraphics{graphics/sec.png}
603\caption{}
604\end{figure}
605
606\[\operatorname{sec} \theta = {1 \over \cos \theta} \> \vert \> \cos \theta \ne 0\]
607
608\begin{itemize}
609\tightlist
610\item
611 \textbf{Domain}
612 \(= \mathbb{R} \setminus \{{{(2n + 1) \pi} \over 2 } : n \in \mathbb{Z}\}\)
613\item
614 \textbf{Range} \(= \mathbb{R} \setminus (-1, 1)\)
615\item
616 \textbf{Turning points} at
617 \(\theta = n\pi \> \vert \> n \in \mathbb{Z}\)
618\item
619 \textbf{Asymptotes} at
620 \(\theta = {{(2n + 1) \pi} \over 2} \> \vert \> n \in \mathbb{Z}\)
621\end{itemize}
622
623\subsubsection{Cotangent}\label{cotangent}
624
625\begin{figure}
626\centering
627\includegraphics{graphics/cot.png}
628\caption{}
629\end{figure}
630
631\[\operatorname{cot} \theta = {{\cos \theta} \over {\sin \theta}} \> \vert \> \sin \theta \ne 0\]
632
633\begin{itemize}
634\tightlist
635\item
636 \textbf{Domain} \(= \mathbb{R} \setminus \{n \pi: n \in \mathbb{Z}\}\)
637\item
638 \textbf{Range} \(= \mathbb{R}\)
639\item
640 \textbf{Asymptotes} at \(\theta = n\pi \> \vert \> n \in \mathbb{Z}\)
641\end{itemize}
642
643\subsubsection{Symmetry properties}\label{symmetry-properties}
644
645\begin{equation}\begin{split}
646 \operatorname{sec} (\pi \pm x) & = -\operatorname{sec} x \\
647 \operatorname{sec} (-x) & = \operatorname{sec} x \\
648 \operatorname{cosec} (\pi \pm x) & = \mp \operatorname{cosec} x \\
649 \operatorname{cosec} (-x) & = - \operatorname{cosec} x \\
650 \operatorname{cot} (\pi \pm x) & = \pm \operatorname{cot} x \\
651 \operatorname{cot} (-x) & = - \operatorname{cot} x
652\end{split}\end{equation}
653
654\subsubsection{Complementary properties}\label{complementary-properties}
655
656\begin{equation}\begin{split}
657 \operatorname{sec} \left({\pi \over 2} - x\right) & = \operatorname{cosec} x \\
658 \operatorname{cosec} \left({\pi \over 2} - x\right) & = \operatorname{sec} x \\
659 \operatorname{cot} \left({\pi \over 2} - x\right) & = \tan x \\
660 \tan \left({\pi \over 2} - x\right) & = \operatorname{cot} x
661\end{split}\end{equation}
662
663\subsubsection{Pythagorean identities}\label{pythagorean-identities}
664
665\begin{equation}\begin{split}
666 1 + \operatorname{cot}^2 x & = \operatorname{cosec}^2 x, \quad \text{where } \sin x \ne 0 \\
667 1 + \tan^2 x & = \operatorname{sec}^2 x, \quad \text{where } \cos x \ne 0
668\end{split}\end{equation}
669
670\subsection{Compound angle formulas}\label{compound-angle-formulas}
671
672\[\cos(x \pm y) = \cos x + \cos y \mp \sin x \sin y\]
673\[\sin(x \pm y) = \sin x \cos y \pm \cos x \sin y\]
674\[\tan(x \pm y) = {{\tan x \pm \tan y} \over {1 \mp \tan x \tan y}}\]
675
676\subsection{Double angle formulas}\label{double-angle-formulas}
677
678\begin{equation}\begin{split}
679 \cos 2x &= \cos^2 x - \sin^2 x \\
680 & = 1 - 2\sin^2 x \\
681 & = 2 \cos^2 x -1
682\end{split}\end{equation}
683
684\[\sin 2x = 2 \sin x \cos x\]
685
686\[\tan 2x = {{2 \tan x} \over {1 - \tan^2 x}}\]
687
688\subsection{Inverse circular
689functions}\label{inverse-circular-functions}
690
691Inverse functions: \(f(f^{-1}(x)) = x, \quad f(f^{-1}(x)) = x\)\\
692Must be 1:1 to find inverse (reflection in \(y=x\)
693
694Domain is restricted to make functions 1:1.
695
696\subsubsection{\texorpdfstring{\(\arcsin\)}{\textbackslash{}arcsin}}\label{arcsin}
697
698\[\sin^{-1}: [-1, 1] \rightarrow \mathbb{R}, \quad \sin^{-1} x = y, \quad \text{where } \sin y = x \text{ and } y \in [{-\pi \over 2}, {\pi \over 2}]\]
699
700\subsubsection{\texorpdfstring{\(\arcos\)}{\textbackslash{}arcos}}\label{arcos}
701
702\[\cos^{-1} \rightarrow \mathbb{R}, \quad \cos^{-1} x = y, \quad \text{where } \cos y = x \text{ and } y \in [0, \pi]\]
703
704\subsubsection{\texorpdfstring{\(\arctan\)}{\textbackslash{}arctan}}\label{arctan}
705
706\[\tan^{-1}: \mathbb{R} \rightarrow \mathbb{R}, \quad \tan^{-1} x = y, \quad \text{where } \tan y = x \text{ and } y \in \left(-{\pi \over 2}, {\pi \over 2}\right)\]
707\# Differential calculus
708
709\subsection{Limits}\label{limits}
710
711\[\lim_{x \rightarrow a}f(x)\]
712
713\(L^-\) - limit from below
714
715\(L^+\) - limit from above
716
717\(\lim_{x \to a} f(x)\) - limit of a point
718
719\begin{itemize}
720\tightlist
721\item
722 Limit exists if \(L^-=L^+\)
723\item
724 If limit exists, point does not.
725\end{itemize}
726
727Limits can be solved using normal techniques (if div 0, factorise)
728
729\subsection{Limit theorems}\label{limit-theorems}
730
731\begin{enumerate}
732\def\labelenumi{\arabic{enumi}.}
733\tightlist
734\item
735 For constant function \(f(x)=k\), \(\lim_{x \rightarrow a} f(x) = k\)
736\item
737 \(\lim_{x \rightarrow a} (f(x) \pm g(x)) = F \pm G\)
738\item
739 \(\lim_{x \rightarrow a} (f(x) \times g(x)) = F \times G\)
740\item
741 \({\lim_{x \rightarrow a} {f(x) \over g(x)}} = {F \over G}, G \ne 0\)
742\end{enumerate}
743
744Corollary: \(\lim_{x \rightarrow a} c \times f(x)=cF\) where \(c=\)
745constant
746
747\subsection{\texorpdfstring{Solving limits for
748\(x\rightarrow\infty\)}{Solving limits for x\textbackslash{}rightarrow\textbackslash{}infty}}\label{solving-limits-for-xrightarrowinfty}
749
750Factorise so that all values of \(x\) are in denominators.
751
752e.g.
753
754\[\lim_{x \rightarrow \infty}{{2x+3} \over {x-2}}={{2+{3 \over x}} \over {1-{2 \over x}}}={2 \over 1} = 2\]
755
756\subsection{Continuous functions}\label{continuous-functions}
757
758A function is continuous if \(L^-=L^+=f(x)\) for all values of \(x\).
759
760\subsection{Gradients of secants and
761tangents}\label{gradients-of-secants-and-tangents}
762
763Secant (chord) - line joining two points on curve
764
765Tangent - line that intersects curve at one point
766
767given \(P(x,y) \quad Q(x+\delta x, y + \delta y)\): gradient of chord
768joining \(P\) and \(Q\) is
769\({m_{PQ}}={\operatorname{rise} \over \operatorname{run}} = {\delta y \over \delta x}\)
770
771As \(Q \rightarrow P, \delta x \rightarrow 0\). Chord becomes tangent
772(two infinitesimal points are equal).
773
774Can also be used with functions, where \(h=\delta x\).
775
776\subsection{First principles
777derivative}\label{first-principles-derivative}
778
779\[f^\prime(x) = \lim_{\delta x \rightarrow 0}{\delta y \over \delta x}={dy \over dx}\]
780
781\[m_{\tan}=\lim_{h \rightarrow 0}f^\prime(x)\]
782
783\[m_{\vec{PQ}}=f^\prime(x)\]
784
785first principles derivative:
786\[{m_{\text{tangent at }P} =\lim_{h \rightarrow 0}}{{f(x+h)-f(x)}\over h}\]
787
788\subsection{Gradient at a point}\label{gradient-at-a-point}
789
790Given point \(P(a, b)\) and function \(f(x)\), the gradient is
791\(f^\prime(a)\)
792
793\subsection{\texorpdfstring{Derivatives of
794\(x^n\)}{Derivatives of x\^{}n}}\label{derivatives-of-xn}
795
796\[{d(ax^n) \over dx}=anx^{n-1}\]
797
798If \(x=\) constant, derivative is \(0\)
799
800If \(y=ax^n\), derivative is \(a\times nx^{n-1}\)
801
802If
803\(f(x)={1 \over x}=x^{-1}, \quad f^\prime(x)=-1x^{-2}={-1 \over x^2}\)
804
805If
806\(f(x)=^5\sqrt{x}=x^{1 \over 5}, \quad f^\prime(x)={1 \over 5}x^{-4/5}={1 \over 5 \times ^5\sqrt{x^4}}\)
807
808If \(f(x)=(x-b)^2, \quad f^\prime(x)=2(x-b)\)
809
810\[f^\prime(x)=\lim_{h \rightarrow 0}{{f(x+h)-f(x)} \over h}\]
811
812\subsection{\texorpdfstring{Derivatives of
813\(u \pm v\)}{Derivatives of u \textbackslash{}pm v}}\label{derivatives-of-u-pm-v}
814
815\[{dy \over dx}={du \over dx} \pm {dv \over dx}\] where \(u\) and \(v\)
816are functions of \(x\)
817
818\subsection{Euler's number as a limit}\label{eulers-number-as-a-limit}
819
820\[\lim_{h \rightarrow 0} {{e^h-1} \over h}=1\]
821
822\subsection{\texorpdfstring{Chain rule for
823\((f\circ g)\)}{Chain rule for (f\textbackslash{}circ g)}}\label{chain-rule-for-fcirc-g}
824
825If \(f(x) = h(g(x)) = (h \circ g)(x)\):
826
827\[f^\prime(x) = h^\prime(g(x)) \cdot g^\prime(x)\]
828
829If \(y=h(u)\) and \(u=g(x)\):
830
831\[{dy \over dx} = {dy \over du} \cdot {du \over dx}\]
832\[{d((ax+b)^n) \over dx} = {d(ax+b) \over dx} \cdot n \cdot (ax+b)^{n-1}\]
833
834Used with only one expression.
835
836e.g. \(y=(x^2+5)^7\) - Cannot reasonably expand\\
837Let \(u-x^2+5\) (inner expression)\\
838\({du \over dx} = 2x\)\\
839\(y=u^7\)\\
840\({dy \over du} = 7u^6\)
841
842\subsection{\texorpdfstring{Product rule for
843\(y=uv\)}{Product rule for y=uv}}\label{product-rule-for-yuv}
844
845\[{dy \over dx} = u{dv \over dx} + v{du \over dx}\]
846
847\subsection{\texorpdfstring{Quotient rule for
848\(y={u \over v}\)}{Quotient rule for y=\{u \textbackslash{}over v\}}}\label{quotient-rule-for-yu-over-v}
849
850\[{dy \over dx} = {{v{du \over dx} - u{dv \over dx}} \over v^2}\]
851
852\[f^\prime(x)={{v(x)u^\prime(x)-u(x)v^\prime(x)} \over [v(x)]^2}\]
853
854\subsection{Logarithms}\label{logarithms}
855
856\[\log_b (x) = n \quad \operatorname{where} \hspace{0.5em} b^n=x\]
857
858Wikipedia:
859
860\begin{quote}
861the logarithm of a given number \(x\) is the exponent to which another
862fixed number, the base \(b\), must be raised, to produce that number
863\(x\)
864\end{quote}
865
866\subsubsection{Logarithmic identities}\label{logarithmic-identities}
867
868\(\log_b (xy)=\log_b x + \log_b y\)\\
869\(\log_b x^n = n \log_b x\)\\
870\(\log_b y^{x^n} = x^n \log_b y\)
871
872\subsubsection{Index identities}\label{index-identities}
873
874\(b^{m+n}=b^m \cdot b^n\)\\
875\((b^m)^n=b^{m \cdot n}\)\\
876\((b \cdot c)^n = b^n \cdot c^n\)\\
877\({a^m \div a^n} = {a^{m-n}}\)
878
879\subsubsection{\texorpdfstring{\(e\) as a
880logarithm}{e as a logarithm}}\label{e-as-a-logarithm}
881
882\[\operatorname{if} y=e^x, \quad \operatorname{then} x=\log_e y\]
883\[\ln x = \log_e x\]
884
885\subsubsection{Differentiating
886logarithms}\label{differentiating-logarithms}
887
888\[{d(\log_e x)\over dx} = x^{-1} = {1 \over x}\]
889
890\subsection{Derivative rules}\label{derivative-rules}
891
892\begin{longtable}[]{@{}ll@{}}
893\toprule
894\(f(x)\) & \(f^\prime(x)\)\tabularnewline
895\midrule
896\endhead
897\(\sin x\) & \(\cos x\)\tabularnewline
898\(\sin ax\) & \(a\cos ax\)\tabularnewline
899\(\cos x\) & \(-\sin x\)\tabularnewline
900\(\cos ax\) & \(-a \sin ax\)\tabularnewline
901\(\tan f(x)\) & \(f^2(x) \sec^2f(x)\)\tabularnewline
902\(e^x\) & \(e^x\)\tabularnewline
903\(e^{ax}\) & \(ae^{ax}\)\tabularnewline
904\(ax^{nx}\) & \(an \cdot e^{nx}\)\tabularnewline
905\(\log_e x\) & \(1 \over x\)\tabularnewline
906\(\log_e {ax}\) & \(1 \over x\)\tabularnewline
907\(\log_e f(x)\) & \(f^\prime (x) \over f(x)\)\tabularnewline
908\(\sin(f(x))\) & \(f^\prime(x) \cdot \cos(f(x))\)\tabularnewline
909\(\sin^{-1} x\) & \(1 \over {\sqrt{1-x^2}}\)\tabularnewline
910\(\cos^{-1} x\) & \(-1 \over {sqrt{1-x^2}}\)\tabularnewline
911\(\tan^{-1} x\) & \(1 \over {1 + x^2}\)\tabularnewline
912\bottomrule
913\end{longtable}
914
915\subsection{Reciprocal derivatives}\label{reciprocal-derivatives}
916
917\[{1 \over {dy \over dx}} = {dx \over dy}\]
918
919\subsection{\texorpdfstring{Differentiating
920\(x=f(y)\)}{Differentiating x=f(y)}}\label{differentiating-xfy}
921
922Find \(dx \over dy\). Then
923\({dx \over dy} = {1 \over {dy \over dx}} \implies {dy \over dx} = {1 \over {dx \over dy}}\).
924
925\[{dy \over dx} = {1 \over {dx \over dy}}\]
926
927\subsection{Second derivative}\label{second-derivative}
928
929\[f(x) \longrightarrow f^\prime (x) \longrightarrow f^{\prime\prime}(x)\]
930
931\[\therefore y \longrightarrow {dy \over dx} \longrightarrow {d({dy \over dx}) \over dx} \longrightarrow {d^2 y \over dx^2}\]
932
933Order of polynomial \(n\)th derivative decrements each time the
934derivative is taken
935
936\subsubsection{Points of Inflection}\label{points-of-inflection}
937
938\emph{Stationary point} - point of zero gradient (i.e.
939\(f^\prime(x)=0\))\\
940\emph{Point of inflection} - point of maximum \(|\)gradient\(|\) (i.e.
941\(f^{\prime\prime} = 0\))
942
943\begin{itemize}
944\tightlist
945\item
946 if \(f^\prime (a) = 0\) and \(f^{\prime\prime}(a) > 0\), then point
947 \((a, f(a))\) is a local min (curve is concave up)
948\item
949 if \(f^\prime (a) = 0\) and \(f^{\prime\prime} (a) < 0\), then point
950 \((a, f(a))\) is local max (curve is concave down)
951\item
952 if \(f^{\prime\prime}(a) = 0\), then point \((a, f(a))\) is a point of
953 inflection
954\item
955 if also \(f^\prime(a)=0\), then it is a stationary point of inflection
956\end{itemize}
957
958\begin{figure}
959\centering
960\includegraphics{graphics/second-derivatives.png}
961\caption{}
962\end{figure}
963
964\subsection{Implicit Differentiation}\label{implicit-differentiation}
965
966\textbf{On CAS:} Action \(\rightarrow\) Calculation \(\rightarrow\)
967\texttt{impDiff(y\^{}2+ax=5,\ x,\ y)}. Returns \(y^\prime= \dots\).
968
969Used for differentiating circles etc.
970
971If \(p\) and \(q\) are expressions in \(x\) and \(y\) such that \(p=q\),
972for all \(x\) nd \(y\), then:
973
974\[{dp \over dx} = {dq \over dx} \quad \text{and} \quad {dp \over dy} = {dq \over dy}\]
975
976\subsection{Integration}\label{integration}
977
978\[\int f(x) \cdot dx = F(x) + c \quad \text{where } F^\prime(x) = f(x)\]
979
980\[\int x^n \cdot dx = {x^{n+1} \over n+1} + c\]
981
982\begin{itemize}
983\tightlist
984\item
985 area enclosed by curves
986\item
987 \(+c\) should be shown on each step without \(\int\)
988\end{itemize}
989
990\subsubsection{Integral laws}\label{integral-laws}
991
992\(\int f(x) + g(x) dx = \int f(x) dx + \int g(x) dx\)\\
993\(\int k f(x) dx = k \int f(x) dx\)
994
995\begin{longtable}[]{@{}ll@{}}
996\toprule
997\begin{minipage}[b]{0.42\columnwidth}\raggedright\strut
998\(f(x)\)\strut
999\end{minipage} & \begin{minipage}[b]{0.38\columnwidth}\raggedright\strut
1000\(\int f(x) \cdot dx\)\strut
1001\end{minipage}\tabularnewline
1002\midrule
1003\endhead
1004\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1005\(k\) (constant)\strut
1006\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1007\(kx + c\)\strut
1008\end{minipage}\tabularnewline
1009\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1010\(x^n\)\strut
1011\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1012\({x^{n+1} \over {n+1}} + c\)\strut
1013\end{minipage}\tabularnewline
1014\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1015\(a x^{-n}\)\strut
1016\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1017\(a \cdot \log_e x + c\)\strut
1018\end{minipage}\tabularnewline
1019\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1020\({1 \over {ax+b}}\)\strut
1021\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1022\({1 \over a} \log_e (ax+b) + c\)\strut
1023\end{minipage}\tabularnewline
1024\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1025\((ax+b)^n\)\strut
1026\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1027\({1 \over {a(n+1)}}(ax+b)^{n-1} + c\)\strut
1028\end{minipage}\tabularnewline
1029\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1030\(e^{kx}\)\strut
1031\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1032\({1 \over k} e^{kx} + c\)\strut
1033\end{minipage}\tabularnewline
1034\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1035\(e^k\)\strut
1036\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1037\(e^kx + c\)\strut
1038\end{minipage}\tabularnewline
1039\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1040\(\sin kx\)\strut
1041\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1042\(-{1 \over k} \cos (kx) + c\)\strut
1043\end{minipage}\tabularnewline
1044\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1045\(\cos kx\)\strut
1046\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1047\({1 \over k} \sin (kx) + c\)\strut
1048\end{minipage}\tabularnewline
1049\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1050\(\sec^2 kx\)\strut
1051\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1052\({1 \over k} \tan(kx) + c\)\strut
1053\end{minipage}\tabularnewline
1054\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1055\(1 \over \sqrt{a^2-x^2}\)\strut
1056\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1057\(\sin^{-1} {x \over a} + c \>\vert\> a>0\)\strut
1058\end{minipage}\tabularnewline
1059\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1060\(-1 \over \sqrt{a^2-x^2}\)\strut
1061\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1062\(\cos^{-1} {x \over a} + c \>\vert\> a>0\)\strut
1063\end{minipage}\tabularnewline
1064\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1065\(a \over {a^2-x^2}\)\strut
1066\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1067\(\tan^{-1} {x \over a} + c\)\strut
1068\end{minipage}\tabularnewline
1069\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1070\({f^\prime (x)} \over {f(x)}\)\strut
1071\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1072\(\log_e f(x) + c\)\strut
1073\end{minipage}\tabularnewline
1074\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1075\(g^\prime(x)\cdot f^\prime(g(x)\)\strut
1076\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1077\(f(g(x))\) (chain rule)\strut
1078\end{minipage}\tabularnewline
1079\begin{minipage}[t]{0.42\columnwidth}\raggedright\strut
1080\(f(x) \cdot g(x)\)\strut
1081\end{minipage} & \begin{minipage}[t]{0.38\columnwidth}\raggedright\strut
1082\(\int [f^\prime(x) \cdot g(x)] dx + \int [g^\prime(x) f(x)] dx\)\strut
1083\end{minipage}\tabularnewline
1084\bottomrule
1085\end{longtable}
1086
1087Note \(\sin^{-1} {x \over a} + \cos^{-1} {x \over a}\) is constant for
1088all \(x \in (-a, a)\).
1089
1090\subsubsection{Definite integrals}\label{definite-integrals}
1091
1092\[\int_a^b f(x) \cdot dx = [F(x)]_a^b=F(b)-F(a)\]
1093
1094\begin{itemize}
1095\tightlist
1096\item
1097 Signed area enclosed by:
1098 \(\> y=f(x), \quad y=0, \quad x=a, \quad x=b\).
1099\item
1100 \emph{Integrand} is \(f\).
1101\item
1102 \(F(x)\) may be any integral, i.e. \(c\) is inconsequential
1103\end{itemize}
1104
1105\paragraph{Properties}\label{properties-2}
1106
1107\[\int^b_a f(x) \> dx = \int^c_a f(x) \> dx + \int^b_c f(x) \> dx\]
1108
1109\[\int^a_a f(x) \> dx = 0\]
1110
1111\[\int^b_a k \cdot f(x) \> dx = k \int^b_a f(x) \> dx\]
1112
1113\[\int^b_a f(x) \pm g(x) \> dx = \int^b_a f(x) \> dx \pm \int^b_a g(x) \> dx\]
1114
1115\[\int^b_a f(x) \> dx = - \int^a_b f(x) \> dx\]
1116
1117\subsubsection{Integration by
1118substitution}\label{integration-by-substitution}
1119
1120\[\int f(u) {du \over dx} \cdot dx = \int f(u) \cdot du\]
1121
1122Note \(f(u)\) must be one-to-one \(\implies\) one \(x\) value for each
1123\(y\) value
1124
1125e.g.~for \(y=\int(2x+1)\sqrt{x+4} \cdot dx\):\\
1126let \(u=x+4\)\\
1127\(\implies {du \over dx} = 1\)\\
1128\(\implies x = u - 4\)\\
1129then \(y=\int (2(u-4)+1)u^{1 \over 2} \cdot du\)\\
1130Solve as a normal integral
1131
1132\paragraph{Definite integrals by
1133substitution}\label{definite-integrals-by-substitution}
1134
1135For \(\int^b_a f(x) {du \over dx} \cdot dx\), evaluate new \(a\) and
1136\(b\) for \(f(u) \cdot du\).
1137
1138\subsubsection{Trigonometric
1139integration}\label{trigonometric-integration}
1140
1141\[\sin^m x \cos^n x \cdot dx\]
1142
1143\textbf{\(m\) is odd:}\\
1144\(m=2k+1\) where \(k \in \mathbb{Z}\)\\
1145\(\implies \sin^{2k+1} x = (\sin^2 z)^k \sin x = (1 - \cos^2 x)^k \sin x\)\\
1146Substitute \(u=\cos x\)
1147
1148\textbf{\(n\) is odd:}\\
1149\(n=2k+1\) where \(k \in \mathbb{Z}\)\\
1150\(\implies \cos^{2k+1} x = (\cos^2 x)^k \cos x = (1-\sin^2 x)^k \cos x\)\\
1151Subbstitute \(u=\sin x\)
1152
1153\textbf{\(m\) and \(n\) are even:}\\
1154Use identities:
1155
1156\begin{itemize}
1157\tightlist
1158\item
1159 \(\sin^2x={1 \over 2}(1-\cos 2x)\)
1160\item
1161 \(\cos^2x={1 \over 2}(1+\cos 2x)\)
1162\item
1163 \(\sin 2x = 2 \sin x \cos x\)
1164\end{itemize}
1165
1166\subsection{Partial fractions}\label{partial-fractions}
1167
1168On CAS: Action \(\rightarrow\) Transformation \(\rightarrow\)
1169\texttt{expand/combine}\\
1170or Interactive \(\rightarrow\) Transformation \(\rightarrow\)
1171\texttt{expand} \(\rightarrow\) Partial
1172
1173\subsection{Graphing integrals on CAS}\label{graphing-integrals-on-cas}
1174
1175In main: Interactive \(\rightarrow\) Calculation \(\rightarrow\)
1176\(\int\) (\(\rightarrow\) Definite)\\
1177Restrictions: \texttt{Define\ f(x)=...} \(\rightarrow\)
1178\texttt{f(x)\textbar{}x\textgreater{}1} (e.g.)
1179
1180\subsection{Applications of
1181antidifferentiation}\label{applications-of-antidifferentiation}
1182
1183\begin{itemize}
1184\tightlist
1185\item
1186 \(x\)-intercepts of \(y=f(x)\) identify \(x\)-coordinates of
1187 stationary points on \(y=F(x)\)
1188\item
1189 nature of stationary points is determined by sign of \(y=f(x)\) on
1190 either side of its \(x\)-intercepts
1191\item
1192 if \(f(x)\) is a polynomial of degree \(n\), then \(F(x)\) has degree
1193 \(n+1\)
1194\end{itemize}
1195
1196To find stationary points of a function, substitute \(x\) value of given
1197point into derivative. Solve for \({dy \over dx}=0\). Integrate to find
1198original function.
1199
1200\subsection{Solids of revolution}\label{solids-of-revolution}
1201
1202Approximate as sum of infinitesimally-thick cylinders
1203
1204\subsubsection{\texorpdfstring{Rotation about
1205\(x\)-axis}{Rotation about x-axis}}\label{rotation-about-x-axis}
1206
1207\begin{align*}
1208 V &= \int^{x=b}_{x-a} \pi y^2 \> dx \\
1209 &= \pi \int^b_a (f(x))^2 \> dx
1210\end{align*}
1211
1212\subsubsection{\texorpdfstring{Rotation about
1213\(y\)-axis}{Rotation about y-axis}}\label{rotation-about-y-axis}
1214
1215\begin{align*}
1216 V &= \int^{y=b}_{y=a} \pi x^2 \> dy \\
1217 &= \pi \int^b_a (f(y))^2 \> dy
1218\end{align*}
1219
1220\subsubsection{\texorpdfstring{Regions not bound by
1221\(y=0\)}{Regions not bound by y=0}}\label{regions-not-bound-by-y0}
1222
1223\[V = \pi \int^b_a f(x)^2 - g(x)^2 \> dx\]\\
1224where \(f(x) > g(x)\)
1225
1226\subsection{Length of a curve}\label{length-of-a-curve}
1227
1228\[L = \int^b_a \sqrt{1 + ({dy \over dx})^2} \> dx \quad \text{(Cartesian)}\]
1229
1230\[L = \int^b_a \sqrt{{dx \over dt} + ({dy \over dt})^2} \> dt \quad \text{(parametric)}\]
1231
1232Evaluate on CAS. Or use Interactive \(\rightarrow\) Calculation
1233\(\rightarrow\) Line \(\rightarrow\) \texttt{arcLen}.
1234
1235\subsection{Rates}\label{rates}
1236
1237\subsubsection{Related rates}\label{related-rates}
1238
1239\[{da \over db} \quad \text{(change in } a \text{ with respect to } b)\]
1240
1241\subsubsection{Gradient at a point on parametric
1242curve}\label{gradient-at-a-point-on-parametric-curve}
1243
1244\[{dy \over dx} = {{dy \over dt} \div {dx \over dt}} \> \vert \> {dx \over dt} \ne 0\]
1245
1246\[{d^2 \over dx^2} = {d(y^\prime) \over dx} = {{dy^\prime \over dt} \div {dx \over dt}} \> \vert \> y^\prime = {dy \over dx}\]
1247
1248\subsection{Rational functions}\label{rational-functions}
1249
1250\[f(x) = {P(x) \over Q(x)} \quad \text{where } P, Q \text{ are polynomial functions}\]
1251
1252\subsubsection{Addition of ordinates}\label{addition-of-ordinates}
1253
1254\begin{itemize}
1255\tightlist
1256\item
1257 when two graphs have the same ordinate, \(y\)-coordinate is double the
1258 ordinate
1259\item
1260 when two graphs have opposite ordinates, \(y\)-coordinate is 0 i.e.
1261 (\(x\)-intercept)
1262\item
1263 when one of the ordinates is 0, the resulting ordinate is equal to the
1264 other ordinate
1265\end{itemize}
1266
1267\subsection{Fundamental theorem of
1268calculus}\label{fundamental-theorem-of-calculus}
1269
1270If \(f\) is continuous on \([a, b]\), then
1271
1272\[\int^b_a f(x) \> dx = F(b) - F(a)\]
1273
1274where \(F\) is any antiderivative of \(f\)
1275
1276\subsection{Differential equations}\label{differential-equations}
1277
1278One or more derivatives
1279
1280\textbf{Order} - highest power inside derivative\\
1281\textbf{Degree} - highest power of highest derivative\\
1282e.g. \({\left(dy^2 \over d^2 x\right)}^3\): order 2, degree 3
1283
1284\subsubsection{Verifying solutions}\label{verifying-solutions}
1285
1286Start with \(y=\dots\), and differentiate. Substitute into original
1287equation.
1288
1289\subsubsection{Function of the dependent
1290variable}\label{function-of-the-dependent-variable}
1291
1292If \({dy \over dx}=g(y)\), then
1293\({dx \over dy} = 1 \div {dy \over dx} = {1 \over g(y)}\). Integrate
1294both sides to solve equation. Only add \(c\) on one side. Express
1295\(e^c\) as \(A\).
1296
1297\subsubsection{Mixing problems}\label{mixing-problems}
1298
1299\[\left({dm \over dt}\right)_\Sigma = \left({dm \over dt}\right)_{\text{in}} - \left({dm \over dt}\right)_{\text{out}}\]
1300
1301\subsubsection{Separation of variables}\label{separation-of-variables}
1302
1303If \({dy \over dx}=f(x)g(y)\), then:
1304
1305\[\int f(x) \> dx = \int {1 \over g(y)} \> dy\]
1306
1307\subsubsection{Using definite integrals to solve
1308DEs}\label{using-definite-integrals-to-solve-des}
1309
1310Used for situations where solutions to \({dy \over dx} = f(x)\) is not
1311required.
1312
1313In some cases, it may not be possible to obtain an exact solution.
1314
1315Approximate solutions can be found by numerically evaluating a definite
1316integral.
1317
1318\subsubsection{Using Euler's method to solve a differential
1319equation}\label{using-eulers-method-to-solve-a-differential-equation}
1320
1321\[{{f(x+h) - f(x)} \over h } \approx f^\prime (x) \quad \text{for small } h\]
1322
1323\[\implies f(x+h) \approx f(x) + hf^\prime(x)\]
1324
1325\end{document}