∫x(xa−a2)(x2−b2)dx=12∫dx2(x2−a2)(x2−b2)
⇒12∫dt(t−a2)(t−b2)
12(a2−b2∫[1(t−a2)−1(t−b2)]dt
=12(a2−b2)log(t−a2)−log(t−b2)+c
=12(a2−b2)log(x2−a2x2−b2)+c