On a piece of paper, draw the graph of a continuous function $y=f(x)$ that satisfies the following three conditions. $$f'(x) < 0\quad\mbox{for}\quad x < -3,$$ $$f'(x) < 0\quad\mbox{for}\quad -3 < x < 3,$$ $$f'(x) < 0\quad\mbox{for}\quad 3 < x$$

Approximate your function by picking a segment from the following for each of the sections of your graph, first for $x < -3$, then for $-3 < x < 3$, and then for $3 < x$. (You should, of course, imagine sliding the pieces vertically up or down to make the function you create be continuous.)

For $x < -3$, use segment
For $-3 < x < 3$, use segment
For $3 < x$, use segment