Answer
(a). $-2$
(b). $-2,-2$
Work Step by Step
(a). Use the formula given in this chapter, we have:
$f'(a)=\lim_{h\to 0}\frac{f(a+h)-f(a)}{h}=\lim_{h\to 0}\frac{6-2(a+h)-(6-2a)}{h}=\lim_{h\to 0}\frac{-2h}{h}=-2$
Thus the derivative of this function is a constant.
(b). $f'(2)=f'(-2)=-2$
