Question

Express the function graphed on the axes below as a piecewise function.

Answer 1

first off, let's get the equation of each line, now, let's notice they're lines, thus we can just use two points from each and the point-slope form to get it, so let's do so, Check the picture below.

`(\stackrel{x_1}{-3}~,~\stackrel{y_1}{0})\qquad(\stackrel{x_2}{-6}~,~\stackrel{y_2}{6})\\\\\\% slope = m\stackrel{slope}{m}\implies\cfrac{\stackrel{rise}{\stackrel{y_2}{6}-\stackrel{y1}{0}}}{\underset{run}{\underset{x_2}{-6}-\underset{x_1}{(-3)}}}\implies \cfrac{6}{-6+3}\implies \cfrac{6}{-3}\implies -2`

`\begin{array}ll\cline{1-1}\textit{point-slope form}\\\cline{1-1}\\y-y_1=m(x-x_1)\\\\\cline{1-1}\end{array}\implies y-\stackrel{y_1}{0}=\stackrel{m}{-2}(x-\stackrel{x_1}{(-3)})\\\\\\y=-2(x+3)\implies \blacktriangleright y = -2x-6 \blacktriangleleft\\\\[-0.35em]\rule{34em}{0.25pt}`

`(\stackrel{x_1}{4}~,~\stackrel{y_1}{-6})\qquad(\stackrel{x_2}{6}~,~\stackrel{y_2}{-9})\\\\\\% slope = m\stackrel{slope}{m}\implies\cfrac{\stackrel{rise}{\stackrel{y_2}{-9}-\stackrel{y1}{(-6)}}}{\underset{run}{\underset{x_2}{6}-\underset{x_1}{4}}}\implies \cfrac{-9+6}{2}\implies \cfrac{-3}{2}`

`\begin{array}c\cline{1-1}\textit{point-slope form}\\\cline{1-1}\\y-y_1=m(x-x_1)\\\\\cline{1-1}\end{array}\implies y-\stackrel{y_1}{(-6)}=\stackrel{m}{-\cfrac{3}{2}}(x-\stackrel{x_1}{4})\implies y+6=-\cfrac{3}{2}(x-4)\\\\\\y+6=-\cfrac{3x}{2}+6\implies \blacktriangleright y = -\cfrac{3x}{2} \blacktriangleleft`

now, if we look at the first line, it has a hole when x = -1, however is going upwards to the left otherwise, so we can say the equation includes values to the left of x = -1.

the second equation has a hole when x = 2, so we can say that the equation includes values from x = +2 onwards.

`f(x) = \begin{cases}-2x-6&,~~ x < -1\\[1em]-\cfrac{3x}{2}&,~~x>2\end{cases}`