# Calculus Simple Fraction Differentiation Help

• September 27th 2010, 11:14 PM
Dex
Calculus Simple Fraction Differentiation Help
Hello, Can you explain to me how to differentiate (find f '(x) ) for fractions? I get confused.

$f(x)=\frac{x^3}{3}$

and

$f(x)=\frac{1}{x^2}$

thanks!
• September 27th 2010, 11:17 PM
Prove It
Write the first as $f(x) = \frac{1}{3}x^3$ and differentiate as normal.

Write the second as $f(x) = x^{-2}$ and differentiate as normal.

Be sure to convert your answers to the same form they were originally written in.
• September 27th 2010, 11:23 PM
Dex
okay, I understand the first question now :) , But don't quiet understand why the 2 is negative.
• September 27th 2010, 11:31 PM
Prove It
Because $a^{-n} = \frac{1}{a^n}$. Basic index law.