Originally Posted by

**astuart** Hello,

I'm supposed to find the derivative of the following.

$\displaystyle (4/3)Pi (r)^3$

Using the form $\displaystyle (d/dx)f(x)$, or turning F(x) into F'(x) (Prime).

Anyway, I'm supposed to **solve(?)** r=2/3 **<-- this equation is already solved**

but I'm not sure how I'm supposed to turn this function into F'(x).

I think I'm supposed to do something like

$\displaystyle (4/3)Pi (3r)^2$

But I'm not sure how I should be applying the exponent when r = 2/3 - or whether I'm on the right track in that case.

Any tips?

Cheers