f''(x)=(-6x-4)/25x^9/5

The critical numbers for this problem are -2/3 and 0. However the 0 wasn't defined at f' or in f and I used as a critical number for f'. So will 0 still be a critical number again for f''?

Question

f''(x)=(-6x-4)/25x^9/5

The critical numbers for this problem are -2/3 and 0. However the 0 wasn't defined at f' or in f  and I used as a critical number for f'. So will 0 still be a critical number again for f''?

anonymous · Answer

A critical number for f ' is a number where f '(x) = 0 OR where f ' (x) is undefined.

anonymous · Answer

am asking f'' not f' thanks.

anonymous · Answer

Not necessarily. And, sorry, I didnt see f ' '...they are so close together.

anonymous · Answer

thank you. do you mean 0 will not be critical number again for f''

anonymous · Answer

It may or may not be a zero. You would need to find f ' ' (x) and determine the critical points of f ' ' (x).