f(x) = 4/5x

Question

i need to find the derivitave but i don't know how to start this one. I know the derivitave of 4 is just zero, and i know the derivative of 5x is 5. But the answer isn't 0/5. Help please.

Answer 1

Hmmmm. do this..
f(x)=(4/5)*x^-1

remember
g(t)=k t^n
g'=nk t^(n-1)