# Math Help - help finding "u" in a integral

1. ## help finding "u" in a integral

Hi, im working on a definite itegral using subsitution but i cant figure out what term i should subsitute?

Here it is: integral goes from 0 to pi 5xcos(x^2) dx

thank you

2. Use $u=x^2$

3. Thank you! it worked perfect