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\fancyhead[LO,LE]{Year 12 Specialist}
\fancyhead[CO,CE]{Andrew Lorimer}
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\begin{document}
+\title{\vspace{-22mm}Year 12 Specialist\vspace{-4mm}}
+\author{Andrew Lorimer}
+\date{}
+\maketitle
+\vspace{-9mm}
\begin{multicols}{2}
\section{Complex numbers}
\[\mathbb{C}=\{a+bi:a,b\in\mathbb{R}\}\]
-
\begin{align*}
\text{Cartesian form: } & a+bi\\
\text{Polar form: } & r\operatorname{cis}\theta
\subsection*{Operations}
- \definecolor{shade1}{HTML}{ffffff}
- \definecolor{shade2}{HTML}{e6f2ff}
- \definecolor{shade3}{HTML}{cce2ff}
- \begin{tabularx}{\columnwidth}{r|X|X}
+ \begin{tabularx}{\columnwidth}{|r|X|X|}
+ \hline
+ \rowcolor{cas}
& \textbf{Cartesian} & \textbf{Polar} \\
\hline
\(z_1 \pm z_2\) & \((a \pm c)(b \pm d)i\) & convert to \(a+bi\)\\
\hline
\(z_1 \cdot z_2\) & \(ac-bd+(ad+bc)i\) & \(r_1r_2 \operatorname{cis}(\theta_1 + \theta_2)\)\\
\hline
- \(z_1 \div z_2\) & \((z_1 \overline{z_2}) \div |z_2|^2\) & \(\left(\frac{r_1}{r_2}\right) \operatorname{cis}(\theta_1 - \theta_2)\)
+ \(z_1 \div z_2\) & \((z_1 \overline{z_2}) \div |z_2|^2\) & \(\left(\frac{r_1}{r_2}\right) \operatorname{cis}(\theta_1 - \theta_2)\) \\
+ \hline
\end{tabularx}
\subsubsection*{Scalar multiplication in polar form}
\[k\left(r \operatorname{cis}\theta\right)=kr \operatorname{cis}\left(\begin{cases}\theta - \pi & |0<\operatorname{Arg}(z)\le \pi \\ \theta + \pi & |-\pi<\operatorname{Arg}(z)\le 0\end{cases}\right)\]
\subsection*{Conjugate}
-
+ \vspace{-7mm} \hfill \colorbox{cas}{\texttt{conjg(a+bi)}}
\begin{align*}
\overline{z} &= a \mp bi\\
&= r \operatorname{cis}(-\theta)
\end{align*}
- \noindent \colorbox{cas}{On CAS: \texttt{conjg(a+bi)}}
-
\subsubsection*{Properties}
\begin{align*}
\overline{z_1 \pm z_2} &= \overline{z_1}\pm\overline{z_2}\\
\overline{z_1 \cdot z_2} &= \overline{z_1}\cdot\overline{z_2}\\
- \overline{kz} &= k\overline{z} \quad | \quad k \in \mathbb{R}\\
+ \overline{kz} &= k\overline{z} \> \forall \> k \in \mathbb{R}\\
z\overline{z} &= (a+bi)(a-bi)\\
&= a^2 + b^2\\
&= |z|^2
\frac{z_1}{z_2}&=z_1z_2^{-1}\\
&=\frac{z_1\overline{z_2}}{|z_2|^2}\\
&=\frac{(a+bi)(c-di)}{c^2+d^2}\\
- & \qquad \text{(rationalise denominator)}
+ & \text{then rationalise denominator}
\end{align*}
\subsection*{Polar form}
- \begin{align*}
- z&=r\operatorname{cis}\theta\\
- &=r(\cos \theta + i \sin \theta)
- \end{align*}
+ \[ r \operatorname{cis} \theta = r\left( \cos \theta + i \sin \theta \right) \]
\begin{itemize}
\item{\(r=|z|=\sqrt{\operatorname{Re}(z)^2 + \operatorname{Im}(z)^2}\)}
- \item{\(\theta = \operatorname{arg}(z)\) \quad \colorbox{cas}{On CAS: \texttt{arg(a+bi)}}}
+ \item{\(\theta = \operatorname{arg}(z)\) \hfill \colorbox{cas}{\texttt{arg(a+bi)}}}
\item{\(\operatorname{Arg}(z) \in (-\pi,\pi)\) \quad \bf{(principal argument)}}
- \item{\colorbox{cas}{Convert on CAS:}\\ \verb|compToTrig(a+bi)| \(\iff\) \verb|cExpand{r·cisX}|}
\item{Multiple representations:\\\(r\operatorname{cis}\theta=r\operatorname{cis}(\theta+2n\pi)\) with \(n \in \mathbb{Z}\) revolutions}
\item{\(\operatorname{cis}\pi=-1,\qquad \operatorname{cis}0=1\)}
\end{itemize}
+ \begin{cas}
+ \-\hspace{1em}\verb|compToTrig(a+bi)| \(\iff\) \verb|cExpand{r·cisX}|
+ \end{cas}
+
\subsection*{de Moivres' theorem}
- \[(r \operatorname{cis} \theta)^n = r^n \operatorname{cis}(n\theta) \text{ where } n \in \mathbb{Z}\]
+ \begin{theorembox}{}
+ \[(r \operatorname{cis} \theta)^n = r^n \operatorname{cis}(n\theta) \text{ where } n \in \mathbb{Z}\]
+ \end{theorembox}
\subsection*{Complex polynomials}
\hline
\end{tabularx}
+ \begin{theorembox}{title=Factor theorem}
+ If \(\beta z + \alpha\) is a factor of \(P(z)\), \\
+ \-\hspace{1em}then \(P(-\dfrac{\alpha}{\beta})=0\).
+ \end{theorembox}
+
\subsection*{\(n\)th roots}
\(n\)th roots of \(z=r\operatorname{cis}\theta\) are:
\addplot[gray, dotted, thick, domain=-35:35] {-1.5708} node [black, font=\footnotesize, above left, pos=1] {\(y=-\frac{\pi}{2}\)};
\end{axis}
\end{tikzpicture}
-\columnbreak
+
+ \subsection*{Mensuration}
+
+ \begin{tikzpicture}[draw=blue!70,thick]
+ \filldraw[fill=lblue] circle (2cm);
+ \filldraw[fill=white]
+ (320:2cm) node[right] {}
+ -- (220:2cm) node[left] {}
+ arc[start angle=220, end angle=320, radius=2cm]
+ -- cycle;
+ \node {Major Segment};
+ \node at (-90:2) {Minor Segment};
+
+ \begin{scope}[xshift=4.5cm]
+ \draw circle (2cm);
+ \filldraw[fill=lblue]
+ (320:2cm) node[right] {}
+ -- (0,0) node[above] {}
+ -- (220:2cm) node[left] {}
+ arc[start angle=220, end angle=320, radius=2cm]
+ -- cycle;
+ \node at (90:1cm) {Major Sector};
+ \node at (-90:1.5) {Minor Sector};
+ \end{scope}
+ \end{tikzpicture}
+
+ \subsubsection*{Sectors}
+
+ \begin{align*}
+ A &= \pi r^2 \dfrac{\theta}{2\pi} \\
+ &= \dfrac{r^2 \theta}{2}
+ \end{align*}
+
+ \subsubsection*{Segments}
+
+ \[ A = \dfrac{r^2}{2} \left( \theta = \sin \theta \right) \]
+
+ \subsubsection*{Chords}
+
+ \begin{align*}
+ \operatorname{crd} \theta &= \sqrt{(1 - \cos\theta)^2 + \sin^2 \theta} \\
+ &= \sqrt{2 - 2\cos\theta} \\
+ &= 2 \sin \left(\dfrac{\theta}{2}\right)
+ \end{align*}
+
\section{Differential calculus}
+ \[f^\prime(x) = \lim_{\delta x \rightarrow 0}{\delta y \over \delta x}={\frac{dy}{dx}}\]
+
\subsection*{Limits}
\[\lim_{x \rightarrow a}f(x)\]
\(f(x)\) is continuous \(\iff L^-=L^+=f(x) \> \forall x\)
\end{enumerate}
- \subsection*{Gradients of secants and tangents}
+ \subsection*{Gradients}
\textbf{Secant (chord)} - line joining two points on curve\\
\textbf{Tangent} - line that intersects curve at one point
- \subsection*{First principles derivative}
-
- \[f^\prime(x) = \lim_{\delta x \rightarrow 0}{\delta y \over \delta x}={\frac{dy}{dx}}\]
-
- \subsubsection*{Logarithmic identities}
+ \subsubsection*{Points of Inflection}
- \(\log_b (xy)=\log_b x + \log_b y\)\\
- \(\log_b x^n = n \log_b x\)\\
- \(\log_b y^{x^n} = x^n \log_b y\)
+ \emph{Stationary point} - i.e.
+ \(f^\prime(x)=0\)\\
+ \emph{Point of inflection} - max \(|\)gradient\(|\) (i.e.
+ \(f^{\prime\prime} = 0\))
- \subsubsection*{Index identities}
+ \subsubsection*{Strictly increasing/decreasing}
- \(b^{m+n}=b^m \cdot b^n\)\\
- \((b^m)^n=b^{m \cdot n}\)\\
- \((b \cdot c)^n = b^n \cdot c^n\)\\
- \({a^m \div a^n} = {a^{m-n}}\)
+ For \(x_2\) and \(x_1\) where \(x_2 > x_1\):
- \subsection*{Reciprocal derivatives}
+ \textbf{strictly increasing}\\
+ \-\hspace{1em}where \(f(x_2) > f(x_1)\) or \(f^\prime(x)>0\)
- \[\frac{1}{\frac{dy}{dx}} = \frac{dx}{dy}\]
+ \textbf{strictly decreasing}\\
+ \hspace{1em}where \(f(x_2) < f(x_1)\) or \(f^\prime(x)<0\)
+ \begin{warning}
+ Endpoints are included, even where \(\boldsymbol{\frac{dy}{dx}=0}\)
+ \end{warning}
- \subsection*{Differentiating \(x=f(y)\)}
- Find \(\dfrac{dx}{dy}\), then \(\dfrac{dy}{dx} = \dfrac{1}{\left(\dfrac{dx}{dy}\right)}\)
\subsection*{Second derivative}
\begin{align*}f(x) \longrightarrow &f^\prime (x) \longrightarrow f^{\prime\prime}(x)\\
\noindent Order of polynomial \(n\)th derivative decrements each time the derivative is taken
- \subsubsection*{Points of Inflection}
- \emph{Stationary point} - i.e.
- \(f^\prime(x)=0\)\\
- \emph{Point of inflection} - max \(|\)gradient\(|\) (i.e.
- \(f^{\prime\prime} = 0\))
+ \subsection*{Slope fields}
+ \begin{tikzpicture}[declare function={diff(\x,\y) = \x+\y;}]
+ \begin{axis}[axis equal, ymin=-4, ymax=4, xmin=-4, xmax=4, ticks=none, enlargelimits=true, ]
+ \addplot[thick, orange, domain=-4:2] {e^(x)-x-1};
+ \pgfplotsinvokeforeach{-4,...,4}{%
+ \draw[gray] ( {#1 -0.1}, {4 - diff(#1, 4) *0.1}) -- ( {#1 +0.1}, {4 + diff(#1, 4) *0.1});
+ \draw[gray] ( {#1 -0.1}, {3 - diff(#1, 3) *0.1}) -- ( {#1 +0.1}, {3 + diff(#1, 3) *0.1});
+ \draw[gray] ( {#1 -0.1}, {2 - diff(#1, 2) *0.1}) -- ( {#1 +0.1}, {2 + diff(#1, 2) *0.1});
+ \draw[gray] ( {#1 -0.1}, {1 - diff(#1, 1) *0.1}) -- ( {#1 +0.1}, {1 + diff(#1, 1) *0.1});
+ \draw[gray] ( {#1 -0.1}, {0 - diff(#1, 0) *0.1}) -- ( {#1 +0.1}, {0 + diff(#1, 0) *0.1});
+ \draw[gray] ( {#1 -0.1}, {-1 - diff(#1, -1) *0.1}) -- ( {#1 +0.1}, {-1 + diff(#1, -1) *0.1});
+ \draw[gray] ( {#1 -0.1}, {-2 - diff(#1, -2) *0.1}) -- ( {#1 +0.1}, {-2 + diff(#1, -2) *0.1});
+ \draw[gray] ( {#1 -0.1}, {-3 - diff(#1, -3) *0.1}) -- ( {#1 +0.1}, {-3 + diff(#1, -3) *0.1});
+ \draw[gray] ( {#1 -0.1}, {-4 - diff(#1, -4) *0.1}) -- ( {#1 +0.1}, {-4 + diff(#1, -4) *0.1});
+ }
+ \end{axis}
+ \end{tikzpicture}
\begin{table*}[ht]
\centering
- \begin{tabularx}{\textwidth}{rXXX}
+ \begin{tabularx}{\textwidth}{|r|Y|Y|Y|}
\hline
- \rowcolor{shade2}
- & \centering\(\dfrac{d^2 y}{dx^2} > 0\) & \centering \(\dfrac{d^2y}{dx^2}<0\) & \(\dfrac{d^2y}{dx^2}=0\) (inflection) \\[1.5em]
+ \rowcolor{lblue}
+ & \adjustbox{margin=0 1ex, valign=m}{\centering\(\dfrac{d^2 y}{dx^2} > 0\)} & \adjustbox{margin=0 1ex, valign=m}{\centering \(\dfrac{d^2y}{dx^2}<0\)} & \adjustbox{margin=0 1ex, valign=m}{\(\dfrac{d^2y}{dx^2}=0\) (inflection)} \\
\hline
\(\dfrac{dy}{dx}>0\) &
\makecell{\\\begin{tikzpicture}\begin{axis}[axis x line=none, axis y line=none, xmin=-3, xmax=0.8, scale=0.2, samples=50, unbounded coords=jump] \addplot[blue] {(e^(x)}; \addplot[red] {x/2.5+0.75}; \end{axis}\end{tikzpicture} \\Rising (concave up)}&
\end{table*}
\begin{itemize}
\item
- if \(f^\prime (a) = 0\) and \(f^{\prime\prime}(a) > 0\), then point
- \((a, f(a))\) is a local min (curve is concave up)
+ \(f^\prime (a) = 0, \> f^{\prime\prime}(a) > 0\) \\
+ \textbf{local min} at \((a, f(a))\) (concave up)
\item
- if \(f^\prime (a) = 0\) and \(f^{\prime\prime} (a) < 0\), then point
- \((a, f(a))\) is local max (curve is concave down)
+ \(f^\prime (a) = 0, \> f^{\prime\prime} (a) < 0\) \\
+ \textbf{local max} at \((a, f(a))\) (concave down)
\item
- if \(f^{\prime\prime}(a) = 0\), then point \((a, f(a))\) is a point of
- inflection
+ \(f^{\prime\prime}(a) = 0\) \\
+ \textbf{point of inflection} at \((a, f(a))\)
\item
- if also \(f^\prime(a)=0\), then it is a stationary point of inflection
+ \(f^{\prime\prime}(a) = 0, \> f^\prime(a)=0\) \\
+ stationary point of inflection at \((a, f(a)\)
\end{itemize}
\subsection*{Implicit Differentiation}
\begin{cas}
Action \(\rightarrow\) Calculation \\
- \hspace{1em}\texttt{impDiff(y\^{}2+ax=5,\ x,\ y)} \hfill(returns \(y^\prime= \dots\))
+ \-\hspace{1em}\texttt{impDiff(y\^{}2+ax=5,\ x,\ y)}
\end{cas}
- \subsection*{Slope fields}
+ \subsection*{Function of the dependent
+ variable}
- \begin{tikzpicture}[declare function={diff(\x,\y) = \x+\y;}]
- \begin{axis}[axis equal, ymin=-4, ymax=4, xmin=-4, xmax=4, ticks=none, enlargelimits=true, ]
- \addplot[thick, orange, domain=-4:2] {e^(x)-x-1};
- \pgfplotsinvokeforeach{-4,...,4}{%
- \draw[gray] ( {#1 -0.1}, {4 - diff(#1, 4) *0.1}) -- ( {#1 +0.1}, {4 + diff(#1, 4) *0.1});
- \draw[gray] ( {#1 -0.1}, {3 - diff(#1, 3) *0.1}) -- ( {#1 +0.1}, {3 + diff(#1, 3) *0.1});
- \draw[gray] ( {#1 -0.1}, {2 - diff(#1, 2) *0.1}) -- ( {#1 +0.1}, {2 + diff(#1, 2) *0.1});
- \draw[gray] ( {#1 -0.1}, {1 - diff(#1, 1) *0.1}) -- ( {#1 +0.1}, {1 + diff(#1, 1) *0.1});
- \draw[gray] ( {#1 -0.1}, {0 - diff(#1, 0) *0.1}) -- ( {#1 +0.1}, {0 + diff(#1, 0) *0.1});
- \draw[gray] ( {#1 -0.1}, {-1 - diff(#1, -1) *0.1}) -- ( {#1 +0.1}, {-1 + diff(#1, -1) *0.1});
- \draw[gray] ( {#1 -0.1}, {-2 - diff(#1, -2) *0.1}) -- ( {#1 +0.1}, {-2 + diff(#1, -2) *0.1});
- \draw[gray] ( {#1 -0.1}, {-3 - diff(#1, -3) *0.1}) -- ( {#1 +0.1}, {-3 + diff(#1, -3) *0.1});
- \draw[gray] ( {#1 -0.1}, {-4 - diff(#1, -4) *0.1}) -- ( {#1 +0.1}, {-4 + diff(#1, -4) *0.1});
- }
- \end{axis}
- \end{tikzpicture}
+ If \({\frac{dy}{dx}}=g(y)\), then
+ \(\frac{dx}{dy} = 1 \div \frac{dy}{dx} = \frac{1}{g(y)}\). Integrate both sides to solve equation. Only add \(c\) on one side. Express
+ \(e^c\) as \(A\).
+
+ \subsection*{Reciprocal derivatives}
+
+ \[\frac{1}{\frac{dy}{dx}} = \frac{dx}{dy}\]
+
+ \subsection*{Differentiating \(x=f(y)\)}
+ Find \(\dfrac{dx}{dy}\), then \(\dfrac{dy}{dx} = \dfrac{1}{\left(\dfrac{dx}{dy}\right)}\)
\subsection*{Parametric equations}
- For each point on \(\left( f(t), g(t) \right)\):
\begin{align*}
\dfrac{dy}{dt} &= \dfrac{dy}{dx} \cdot \dfrac{dx}{dt} \\
\therefore \dfrac{dy}{dx} &= \dfrac{\left(\dfrac{dy}{dt}\right)}{\left(\dfrac{dx}{dt}\right)} \text{ provided } \dfrac{dx}{dt} \ne 0 \\
- \text{Also...} \\
\dfrac{d^2y}{dx^2} &= \dfrac{\left(\dfrac{dy^\prime}{dt}\right)}{\left(\dfrac{dx}{dt}\right)} \text{ where } y^\prime = \dfrac{dy}{dx}
\end{align*}
\[\int f(x) \cdot dx = F(x) + c \quad \text{where } F^\prime(x) = f(x)\]
- \subsubsection*{Definite integrals}
-
- \[\int_a^b f(x) \cdot dx = [F(x)]_a^b=F(b)-F(a)\]
-
- \begin{itemize}
-
- \item
- Signed area enclosed by\\
- \(\> y=f(x), \quad y=0, \quad x=a, \quad x=b\).
- \item
- \emph{Integrand} is \(f\).
- \end{itemize}
-
\subsubsection*{Properties}
\begin{align*}
\(\sin 2x = 2 \sin x \cos x\)
\end{itemize}
+ \subsection*{Separation of variables}
+
+ If \({\frac{dy}{dx}}=f(x)g(y)\), then:
+
+ \[\int f(x) \> dx = \int \frac{1}{g(y)} \> dy\]
+
\subsection*{Partial fractions}
To factorise \(f(x) = \frac{\delta}{\alpha \cdot \beta}\):
\begin{cas}
Action \(\rightarrow\) Transformation:\\
- \hspace{1em} \texttt{expand(..., x)}
+ \-\hspace{1em} \texttt{expand(..., x)}
To reverse, use \texttt{combine(...)}
\end{cas}
+ \subsection*{Integrating \(\boldsymbol{\dfrac{dy}{dx} = g(y)}\)}
+
+ \[ \text{if } \dfrac{dy}{dx} = g(y), \text{ then } x = \int{\dfrac{1}{g(y)}} \> dy \]
+
\subsection*{Graphing integrals on CAS}
\begin{cas}
\textbf{In main:} Interactive \(\rightarrow\) Calculation \(\rightarrow\) \(\int\)\\
- Restrictions: \texttt{Define\ f(x)=..} then \texttt{f(x)\textbar{}x\textgreater{}..}
+ For restrictions, \texttt{Define\ f(x)=...} then \texttt{f(x)\textbar{}x\textgreater{}...}
\end{cas}
- \subsection*{Applications of antidifferentiation}
-
- \begin{itemize}
-
- \item
- \(x\)-intercepts of \(y=f(x)\) identify \(x\)-coordinates of
- stationary points on \(y=F(x)\)
- \item
- nature of stationary points is determined by sign of \(y=f(x)\) on
- either side of its \(x\)-intercepts
- \item
- if \(f(x)\) is a polynomial of degree \(n\), then \(F(x)\) has degree
- \(n+1\)
- \end{itemize}
-
- To find stationary points of a function, substitute \(x\) value of given
- point into derivative. Solve for \({\frac{dy}{dx}}=0\). Integrate to find
- original function.
-
\subsection*{Solids of revolution}
Approximate as sum of infinitesimally-thick cylinders
\subsection*{Length of a curve}
- \[L = \int^b_a \sqrt{1 + ({\frac{dy}{dx}})^2} \> dx \quad \text{(Cartesian)}\]
-
- \[L = \int^b_a \sqrt{{\frac{dx}{dt}} + ({\frac{dy}{dt}})^2} \> dt \quad \text{(parametric)}\]
+ For length of \(f(x)\) from \(x=a \rightarrow x=b\):
+ \begin{align*}
+ &\text{Cartesian} \> & L &= \int^b_a \sqrt{1 + \left(\dfrac{dy}{dx}\right)^2} \> dx \\
+ &\text{Parametric} \> & L & = \int^b_a \sqrt{\left(\dfrac{dx}{dt}\right)^2 + \left(\dfrac{dy}{dt}\right)^2} \> dt
+ \end{align*}
\begin{cas}
\begin{enumerate}[label=\alph*), leftmargin=5mm]
\end{enumerate}
\end{cas}
+ \subsection*{Applications of antidifferentiation}
+
+ \begin{itemize}
+
+ \item
+ \(x\)-intercepts of \(y=f(x)\) identify \(x\)-coordinates of
+ stationary points on \(y=F(x)\)
+ \item
+ nature of stationary points is determined by sign of \(y=f(x)\) on
+ either side of its \(x\)-intercepts
+ \item
+ if \(f(x)\) is a polynomial of degree \(n\), then \(F(x)\) has degree
+ \(n+1\)
+ \end{itemize}
+
+ To find stationary points of a function, substitute \(x\) value of given
+ point into derivative. Solve for \({\frac{dy}{dx}}=0\). Integrate to find
+ original function.
+
\subsection*{Rates}
\subsubsection*{Gradient at a point on parametric curve}
\[f(x) = \frac{P(x)}{Q(x)} \quad \text{where } P, Q \text{ are polynomial functions}\]
- \subsubsection*{Addition of ordinates}
-
- \begin{itemize}
-
- \item
- when two graphs have the same ordinate, \(y\)-coordinate is double the
- ordinate
- \item
- when two graphs have opposite ordinates, \(y\)-coordinate is 0 i.e.
- (\(x\)-intercept)
- \item
- when one of the ordinates is 0, the resulting ordinate is equal to the
- other ordinate
- \end{itemize}
-
\subsection*{Fundamental theorem of calculus}
If \(f\) is continuous on \([a, b]\), then
\textbf{Degree} - highest power of highest derivative\\
e.g. \({\left(\dfrac{dy^2}{d^2} x\right)}^3\) \qquad order 2, degree 3
- \subsubsection*{Verifying solutions}
-
- Start with \(y=\dots\), and differentiate. Substitute into original
- equation.
-
- \subsubsection*{Function of the dependent
- variable}
-
- If \({\frac{dy}{dx}}=g(y)\), then
- \(\frac{dx}{dy} = 1 \div \frac{dy}{dx} = \frac{1}{g(y)}\). Integrate both sides to solve equation. Only add \(c\) on one side. Express
- \(e^c\) as \(A\).
+ \begin{warning}
+ To verify solutions, find \(\frac{dy}{dx}\) from \(y\) and substitute into original
+ \end{warning}
\[\left(\frac{dm}{dt}\right)_\Sigma = \left(\frac{dm}{dt}\right)_{\text{in}} - \left(\frac{dm}{dt}_{\text{out}}\right)\]
- \subsubsection*{Separation of variables}
+ \subsection*{Euler's method}
- If \({\frac{dy}{dx}}=f(x)g(y)\), then:
+ \[\dfrac{f(x+h) - f(x)}{h} \approx f^\prime (x) \quad \text{for small } h\]
- \[\int f(x) \> dx = \int \frac{1}{g(y)} \> dy\]
+ \[\implies f(x+h) \approx f(x) + hf^\prime(x)\]
- \subsubsection*{Euler's method for solving DEs}
+ \begin{theorembox}{}
+ If \(\dfrac{dy}{dx} = g(x)\) with \(x_0 = a\) and \(y_0 = b\), then:
+ \begin{align*}
+ x_{n+1} &= x_n + h \\
+ y_{n+1} &= y_n + hg(x_n)
+ \end{align*}
+ \end{theorembox}
- \[\frac{f(x+h) - f(x)}{h} \approx f^\prime (x) \quad \text{for small } h\]
- \[\implies f(x+h) \approx f(x) + hf^\prime(x)\]
\include{calculus-rules}
\subsubsection*{Velocity-time graphs}
- \begin{itemize}
- \item Displacement: \textit{signed} area between graph and \(t\) axis
- \item Distance travelled: \textit{total} area between graph and \(t\) axis
- \end{itemize}
+ \begin{description}[nosep, labelindent=0.5cm, leftmargin=0.5\columnwidth]
+ \item[Displacement:] \textit{signed} area
+ \item[Distance travelled:] \textit{total} area
+ \end{description}
\[ \text{acceleration} = \frac{d^2x}{dt^2} = \frac{dv}{dt} = v\frac{dv}{dx} = \frac{d}{dx}\left(\frac{1}{2}v^2\right) \]
\begin{center}
\renewcommand{\arraystretch}{1}
\begin{tabular}{ l r }
- \hline & no \\ \hline
- \(v=u+at\) & \(x\) \\
- \(v^2 = u^2+2as\) & \(t\) \\
- \(s = \frac{1}{2} (v+u)t\) & \(a\) \\
- \(s = ut + \frac{1}{2} at^2\) & \(v\) \\
- \(s = vt- \frac{1}{2} at^2\) & \(u\) \\ \hline
- \end{tabular}
+ \hline & no \\ \hline
+ \(v=u+at\) & \(x\) \\
+ \(v^2 = u^2+2as\) & \(t\) \\
+ \(s = \frac{1}{2} (v+u)t\) & \(a\) \\
+ \(s = ut + \frac{1}{2} at^2\) & \(v\) \\
+ \(s = vt- \frac{1}{2} at^2\) & \(u\) \\ \hline
+ \end{tabular}
\end{center}
\[ v_{\text{avg}} = \frac{\Delta\text{position}}{\Delta t} \]
\end{align*}
\noindent \textbf{Distance travelled between \(t=a \rightarrow t=b\):}
- \[= \int^b_a \sqrt{\left(\frac{dx}{dt}\right)^2 + \left(\frac{dy}{dt}\right)^2} \cdot dt \]
+ \begin{align*}
+ &= \int^{b}_{a}{\sqrt{\left(\frac{dx}{dt}\right)^2 + \left(\frac{dy}{dt}\right)^2}} \> dt \tag{2D} \\
+ &= \int^{t=b}_{t=a}{\dfrac{dx}{dt}} \> dt \tag{linear}
+ \end{align*}
\noindent \textbf{Shortest distance between \(\boldsymbol{r}(t_0)\) and \(\boldsymbol{r}(t_1)\):}
\[ = |\boldsymbol{r}(t_1) - \boldsymbol{r}(t_2)| \]