Let
f(x) =
\begin{cases}
-\left(4x+2\right) & \textrm{if }x < -1 \\
2x^{2} & \textrm{if }-1 \leq x \leq 1 \\
2x & \textrm{if }x > 1
\end{cases}

Find a formula forf'(x) .

**Note:** f(x) is differentiable at x=-1 , but is NOT differentiable at x=1 . Can you see why that is so?

Find a formula for

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