Question

Вычислить неопределенный интеграл xsin5xdx

Answer 1

$\int \underbrace {x}_{u}\cdot \underbrace {sin5x\, dx}_{dv}=uv-\int v\, du=-\dfrac{1}{5}\, x\cdot cos5x+\dfrac{1}{5}\int cos5x\, dx=\\\\\\=\dfrac{x}{5}\cdot cos5x+\dfrac{1}{25}\cdot sin5x+C$