# Math Help - integration

1. ## integration

Hi, in my lecture notes it says:

$\int^9_0 2x cos x^2 dx$

equals to

$sin x^2 ]^9_0$

i dont get how they got that

can someone please explain it to me in a very simple way?

2. Originally Posted by Pengu
Hi, in my lecture notes it says:

$\int^9_0 2x cos x^2 dx$

equals to

$sin x^2 ]^9_0$

i dont get how they got that

can someone please explain it to me in a very simple way?
Put x^2 = t, then
2x*dx = dt.
The integration becomes
Int(cost)dt = sin(t) = sin(x^2)