methods / transformations.texon commit [spec] additions to complex graphs and exp identities (4de6207)
   1\definecolor{shade1}{HTML}{ffffff}
   2\definecolor{shade2}{HTML}{e6f2ff}
   3\definecolor{shade3}{HTML}{cce2ff}
   4\section{Transformations}
   5
   6\textbf{Order of operations:} DRT
   7
   8\begin{center}dilations --- reflections --- translations\end{center}
   9
  10\subsection*{Transforming \(x^n\) to \(a(x-h)^n+K\)}
  11
  12\begin{itemize}
  13\tightlist
  14\item
  15  dilation factor of \(|a|\) units parallel to \(y\)-axis or from
  16  \(x\)-axis
  17\item
  18  if \(a<0\), graph is reflected over \(x\)-axis
  19\item
  20  translation of \(k\) units \(\parallel y\)-axis/from \(x\)-axis
  21\item
  22  translation of \(h\) units \(\parallel x\)-axis/from \(y\)-axis
  23\item
  24  for \((ax)^n\), dilation factor is \(\frac{1}{a} \> \parallel x\)-axis/from \(y\)-axis
  25\item
  26  when \(0 < |a| < 1\), graph becomes closer to axis
  27\end{itemize}
  28
  29\subsection*{Transforming \(f(x)\) to \(y=Af[n(x+c)]+b\)}
  30
  31Applies to exponential, log, trig, \(e^x\), polynomials.\\
  32Functions must be written in form \(y=Af[n(x+c)]+b\)
  33
  34\begin{itemize}
  35\tightlist
  36\item
  37  dilation by factor \(|A|\) from \(x\)-axis (if \(A<0\), reflection
  38  across \(y\)-axis)
  39\item
  40  dilation by factor \(1 \over n\) from \(y\)-axis (if \(n<0\),
  41  reflection across \(x\)-axis)
  42\item
  43  translation of \(c\) units from \(y\)-axis (\(x\)-shift)
  44\item
  45  translation of \(b\) units from \(x\)-axis (\(y\)-shift)
  46\end{itemize}
  47
  48\subsection*{Dilations}
  49
  50Two pairs of equivalent processes for \(y=f(x)\):
  51
  52\begin{enumerate}
  53\def\labelenumi{\arabic{enumi}.}
  54\item
  55  \begin{itemize}
  56  \tightlist
  57  \item
  58    Dilating from \(x\)-axis: \((x, y) \rightarrow (x, by)\)
  59  \item
  60    Replacing \(y\) with \(y \over b\) to obtain \(y = b f(x)\)
  61  \end{itemize}
  62\item
  63  \begin{itemize}
  64  \tightlist
  65  \item
  66    Dilating from \(y\)-axis: \((x, y) \rightarrow (ax, y)\)
  67  \item
  68    Replacing \(x\) with \(x \over a\) to obtain \(y = f({x \over a})\)
  69  \end{itemize}
  70\end{enumerate}
  71
  72For graph of \(y={1 \over x}\), horizontal \& vertical dilations are
  73equivalent (symmetrical). If \(y={a \over x}\), graph is contracted
  74rather than dilated.
  75
  76\subsection*{Matrix transformations}
  77
  78Find new point \((x^\prime, y^\prime)\). Substitute these into original
  79equation to find image with original variables \((x, y)\).
  80
  81\subsection*{Reflections}
  82
  83\begin{itemize}
  84\tightlist
  85\item
  86  Reflection \textbf{in} axis = reflection \textbf{over} axis =
  87  reflection \textbf{across} axis
  88\item
  89  Translations do not change
  90\end{itemize}
  91
  92\subsection*{Translations}
  93
  94For \(y = f(x)\), these processes are equivalent:
  95
  96\begin{itemize}
  97\tightlist
  98\item
  99  applying the translation \((x, y) \rightarrow (x + h, y + k)\) to the
 100  graph of \(y = f(x)\)
 101\item
 102  replacing \(x\) with \(x-h\) and \(y\) with \(y-k\) to obtain
 103  \(y-k = f(x-h)\)
 104\end{itemize}
 105
 106\subsection*{Power functions}
 107
 108Mostly only on CAS.
 109
 110We can write
 111\(x^{-1 \over n} = {1 \over {x^{1 \over n}}} = {1 \over ^n \sqrt{x}}\)n.\\
 112Domain is:
 113\(\begin{cases} \mathbb{R} \setminus \{0\}\hspace{0.5em} \text{ if }n\text{ is odd} \\ \mathbb{R}^+ \hspace{2.6em}\text{if }n\text{ is even}\end{cases}\)
 114
 115If \(n\) is odd, it is an odd function.
 116
 117\subsubsection*{\(x^{p \over q}\) where \(p, q \in \mathbb{Z}^+\)}
 118
 119\[x^{p \over q} = \sqrt[q]{x^p}\]
 120
 121\begin{itemize}
 122\tightlist
 123\item
 124  if \(p > q\), the shape of \(x^p\) is dominant
 125\item
 126  if \(p < q\), the shape of \(x^{1 \over q}\) is dominant
 127\item
 128  points \((0, 0)\) and \((1, 1)\) will always lie on graph
 129\item
 130  Domain is:
 131  \(\begin{cases} \mathbb{R} \hspace{4em}\text{ if }q\text{ is odd} \\ \mathbb{R}^+ \cup \{0\} \hspace{1em}\text{if }q\text{ is even}\end{cases}\)
 132\end{itemize}
 133