methods / transformations.mdon commit fix image widths and clarify dilation in translation notes (8860d43)
   1---
   2geometry: margin=2cm
   3author: Andrew Lorimer
   4---
   5
   6# Transformation
   7
   8**Order of operations:** DRT - Dilations, Reflections, Translations
   9
  10## Transforming $x^n$ to $a(x-h)^n+K$
  11
  12- $|a|$ is the dilation factor of $|a|$ units parallel to $y$-axis or from $x$-axis
  13- if $a<0$, graph is reflected over $x$-axis
  14- $k$ - translation of $k$ units parallel to $y$-axis or from $x$-axis
  15- $h$ - translation of $h$ units parallel to $x$-axis or from $y$-axis
  16- for $(ax)^n$, dilation factor is $1 \over a$ parallel to $x$-axis or from $y$-axis
  17- when $0 < |a| < 1$, graph becomes closer to axis
  18
  19## Translations
  20
  21For $y = f(x)$, these processes are equivalent:
  22
  23- applying the translation $(x, y) \rightarrow (x + h, y + k)$ to the graph of $y = f(x)$
  24- replacing $x$ with $x − h$ and $y$ with $y − k$ to obtain $y − k = f (x − h)$
  25
  26## Dilations
  27
  28For the graph of $y = f(x)$, there are two pairs of equivalent processes:
  29
  301. - Dilating from $x$-axis: $(x, y) \rightarrow (x, by)$
  31   - Replacing $y$ with $y \over b$ to obtain $y = b f(x)$
  32
  332. - Dilating from $y$-axis: $(x, y) \rightarrow (ax, y)$
  34   - Replacing $x$ with $x \over a$ to obtain $y = f({x \over a})$
  35
  36For graph of $y={1 \over x}$, horizontal & vertical dilations are equivalent (symmetrical). If $y={a \over x}$, graph is contracted rather than dilated.
  37
  38## Transforming $f(x)$ to $y=Af[n(x+c)]+b$#
  39
  40Applies to exponential, log, trig, power, polynomial functions.  
  41Functions must be written in form $y=Af[n(x+c)] + b$
  42
  43$A$ - dilation by factor $A$ from $x$-axis (if $A<0$, reflection across $y$-axis)  
  44$n$ - dilation by factor $1 \over n$ from $y$-axis (if $n<0$, reflection across $x$-axis)  
  45$c$ - translation from $y$-axis ($x$-shift)  
  46$b$ - translation from $x$-axis ($y$-shift)
  47
  48## Power functions
  49
  50**Strictly increasing:**  $f(x_2) > f(x_1)$ where $x_2 > x_1$ (including $x=0$)
  51
  52### Odd and even functions
  53Even when $f(x) = -f(x)$  
  54Odd when $-f(x) = f(-x)$
  55
  56Function is even if it can be reflected across $y$-axis $\implies f(x)=f(-x)$  
  57Function $x^{\pm {p \over q}}$ is odd if $q$ is odd
  58
  59### $x^n$ where $n \in \mathbb{Z}^+$
  60
  61| $n$ is even: | $n$ is odd: |
  62| ------------ | ----------- |
  63|![](graphics/parabola.png){#id .class width=20%} | ![](graphics/cubic.png){#id .class width=20%} |
  64
  65### $x^n$ where $n \in \mathbb{Z}^-$
  66
  67| $n$ is even: | $n$ is odd: |
  68| ------------ | ----------- |
  69|![](graphics/truncus.png){#id .class width=20%} | ![](graphics/hyperbola.png){#id .class width=20%} |
  70
  71### $x^{1 \over n}$ where $n \in \mathbb{Z}^+$
  72
  73| $n$ is even: | $n$ is odd: |
  74| ------------ | ----------- |
  75|![](graphics/square-root-graph.png){#id .class width=20%} | ![](graphics/cube-root-graph.png){#id .class width=20%} |
  76
  77
  78### $x^{-1 \over n}$ where $n \in \mathbb{Z}^+$
  79
  80Mostly only on CAS.
  81
  82We can write $x^{-1 \over n} = {1 \over {x^{1 \over n}}} = {1 \over ^n \sqrt{x}}$n.  
  83Domain is:  $\begin{cases} \mathbb{R} \setminus \{0\}\hspace{0.5em} \text{ if }n\text{ is odd} \\ \mathbb{R}^+ \hspace{2.6em}\text{if }n\text{ is even}\end{cases}$
  84
  85If $n$ is odd, it is an odd function.
  86
  87### $x^{p \over q}$ where $p, q \in \mathbb{Z}^+$
  88
  89$$x^{p \over q} = \sqrt[q]{x^p}$$
  90
  91- if $p > q$, the shape of $x^p$ is dominant
  92- if $p < q$, the shape of $x^{1 \over q}$ is dominant
  93- points $(0, 0)$ and $(1, 1)$ will always lie on graph
  94- Domain is:  $\begin{cases} \mathbb{R} \hspace{4em}\text{ if }q\text{ is odd} \\ \mathbb{R}^+ \cup \{0\} \hspace{1em}\text{if }q\text{ is even}\end{cases}$
  95
  96
  97## Combinations of functions (piecewise/hybrid)
  98
  99$$\text{e.g.}\quad f(x)=\begin{cases} ^3 \sqrt{x}, \hspace{2em} x \le 0 \\ 2, \hspace{3.4em} 0 < x < 2 \\ x, \hspace{3.4em} x \ge 2 \end{cases}$$
 100
 101Open circle - point included  
 102Closed circle - point not included  
 103
 104### Sum, difference, product of functions
 105| | | |
 106|---|-----|-----|
 107|sum|$f+g$|domain $= \text{dom}(f) \cap \text{dom}(g)$|
 108|difference|$f-g$ or $g-f$|domain $=\text{dom}(f) \cap \text{dom}(g)$|
 109|product|$f \times g$|domain $=\text{dom}(f) \cap \text{dom}(g)$|
 110
 111Addition of linear piecewise graphs - add $y$-values at key points
 112
 113Product functions:
 114
 115- product will equal 0 if one of the functions is equal to 0
 116- turning point on one function does not equate to turning point on product
 117
 118## Matrix transformations
 119
 120Find new point $(x^\prime, y^\prime)$. Substitute these into original equation to find image with original variables $(x, y)$.
 121
 122## Composite functions
 123
 124$(f \circ g)(x)$ is defined iff $\operatorname{ran}(g) \subseteq \operatorname{dom}(f)$
 125
 126