find area under graph $\displaystyle y = \frac{1}{x^2}$ between x=1/3 and x=1/2
$\displaystyle
\int_{1/3}^{1/2} \frac {x^-1}{-1}
$
this correct?
then i substitute the intervals?
There should be no integral sign after you've done the integration. It should be $\displaystyle \left[ \frac{x^{-1}}{-1}\right]_{1/3}^{1/2}$, which can be re-written in simpler form as $\displaystyle \left[ - \frac{1}{x}\right]_{1/3}^{1/2}$. Then you substitute the integral terminals in the usual way.