Giải thích các bước giải:
a. \(\int xsinxcosxdx=\int \frac{xsin2x}{2}dx=\frac{1}{2}\int sin(2x)dx=\frac{1}{2}(x\frac{-cos2x}{2})-\int \frac{-cos2x}{2}dx=\frac{1}{2}(x\frac{-cos2x}{2})-(\frac{-1}{2})\int cos2x.dx=-\frac{x
cos2x}{4}+\frac{1}{4}.\frac{sin2x}{2}+C=\frac{xcos2x}{4}+\frac{sin2x}{8}+C\)