Help Please! (:
Consider the function f(x) = 8 (x - 4)^{2/3}. For this function there are two important intervals: (negative infty, A) and (A,infty) where A is a critical number. Find A.

Question

Help Please! (:
Consider the function f(x) = 8 (x - 4)^{2/3}. For this function there are two important intervals:  (negative infty, A) and (A,infty) where  A is a critical number. Find A.

anonymous · Answer

take the derivative, set it equal to zero and solve

anonymous · Answer

ok that was silly, the derivative does not have any zeros
however, it is undefined at $x=4$

anonymous · Answer

Yeah I did the same. the derivative has no zeros so would A = 4? @satellite73

anonymous · Answer

@loser66

loser66 · Answer

what do you want me to do? want to see math tool's answer? there you go: https://www.wolframalpha.com/input/?i=%288%28x-4%29^%282%2F3%29%29%27

loser66 · Answer

don't forget, critical point can be a saddle point or a point the graph "jumps", no need to be the points f(x) turns from decrease to increase or vice versa. In this case, it's 4

anonymous · Answer

Ohhhh. okay. I understand it a bit more now (: thanks!

loser66 · Answer

yw