# Integration with Trigonometric Substitution

 P: 1,754 You don't even need Trig substitution. $$\int x\sqrt{9-x^2}dx$$ $$u=9-x^2$$ $$du=-2xdx \rightarrow xdx=-\frac 1 2 du$$
 P: 4 $$\int x^2\sqrt{9-x^2}dx$$ apropo $$u=x^2\sqrt{9-x^2}dx$$