∫x(1−x)n dx =
(1−x)2−n2−n+(1−x)1−n1−n+c
(1−x)2+n2+n−(1−x)1+n2+n+c
(1−x)2−n2−n−(1−x)1−n1−n+c
(1−x)2−n2+n+(1−x)1−n1+n+c
∫x(1−x)n dx =-∫(1−x)−1(1−x)n dx =-∫1(1−x)n−1 dx+∫1(1−x)n dx
=(1−x)2−n2−n−(1−x)1−n1−n+c