∫xcos(x/2)dx
问题描述:
∫xcos(x/2)dx
答
用分部积分
∫xcos(x/2)dx
=2∫xcos(x/2)d(x/2)
=2∫xdsin(x/2)
=2xsin(x/2)-2∫sin(x/2)dx
=2xsin(x/2)-4∫sin(x/2)d(x/2)
=2xsin(x/2)+4cos(x/2)+C