If f(x)= (the fifth root of x^2) - (8/x) then f`(x) = ?

I started by setting it up as follows

{x^(2/5)} - (8x^-1)

I then used the power rule to get:

{(2/5x)^(-3/5)}-(8x^-2) but that doesn't go through as correct. Can someone point out where I am going wrong?

Thanks