Derivative of Integral I'm having a little trouble with the following problem:
Calculate $F'(x)$:
$F(x)=\int_{1}^{x^{2}}(t-\sin^{2}t) dt$
It says we have to use substitution but I don't see why the answer can't just be:
$x-\sin^{2}x$

$\displaystyle{%
{{\rm d} \over {\rm d}x}
=
2x\,{{\rm d} \over {\rm d}\left(x^{2}\right)}
}$
