anyhow, note the f(x) you have, bearing in mind, you kinda skipped posting it
[tex]\bf slope = {{ m}}= \cfrac{rise}{run} \implies
\cfrac{{{ f(x_2)}}-{{ f(x_1)}}}{{{ x_2}}-{{ x_1}}}\impliedby
\begin{array}{llll}
average\ rate\\
of\ change
\end{array}
\\\\\\
f(x)\qquad
\begin{cases}
x_1=1\\
x_2=-5
\end{cases}\implies \cfrac{f(-5)-f(1)}{-5-1}[/tex]
