Find the interval of increase/decrease of f = x^(1/7) (x+8)
I started to find f' = x^(1/7) + (x+8) (1/7 x^(-6/7)) But when I try to simplify and solve for x, everything gets strange and I know that I am not doing it right. Can you show me the steps, please? Thanks.
Wait, so the first equation is the second derivative? I thought it was the original function.
Edit: But you are right.
x=-1 is one of the zeroes. The other zero is at x=0. However, if you remember the first step after taking the derivative is finding the domain. In this case x <> 0, because 0 in the denominator would be undefined.
Now just test before and after -1 and before and after 0 to find rise/fall.