Let f(x)=[x^3-9x]

[] --- absolute value

a. does f'(x) exist?
b. does f'(3) exist?
c. does f'(-3) exist?
d. determine all extrema of f.

1 answer

I will be happy to critique your thinking. Remember, you need to work on either side of x=3 here, and on either side of x=-3.