I know I'm in calculus but sometimes the algebra kills me.

This is about finding the absolute maximum and minimum. endpoints

X=-8 and x=1

F(x)=x^4/3

f(-8)=(-8)^4/3

f(-8)= ???

How do i solve this step by step,i tried the calculator but its not giving me the right answer, my mathlab says its wrong.

This is an example from my mathlab

F(x)=x^8/3

f(-8)=(-8)^8/3

f(-8)= 256 (I don't know how they got that)