Hello, Can you explain to me how to differentiate (find f '(x) ) for fractions? I get confused.

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

and

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

thanks!

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- Sep 27th 2010, 10:14 PMDexCalculus Simple Fraction Differentiation Help
Hello, Can you explain to me how to differentiate (find f '(x) ) for fractions? I get confused.

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

and

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

thanks! - Sep 27th 2010, 10:17 PMProve It
Write the first as $\displaystyle f(x) = \frac{1}{3}x^3$ and differentiate as normal.

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

Be sure to convert your answers to the same form they were originally written in. - Sep 27th 2010, 10:23 PMDex
okay, I understand the first question now :) , But don't quiet understand why the 2 is negative.

- Sep 27th 2010, 10:31 PMProve It
Because $\displaystyle a^{-n} = \frac{1}{a^n}$. Basic index law.