用分部积分法求下列不定积分 1）∫xsin2xdx 2）∫xlnxdx 3）∫arccosxdx 4）∫xarctanxdx

2）3）4）答案同楼上,1）∫xsin2xdx=(-1/2)∫xdcos2x=(-1/2)xcos2x+(1/2)∫cos2xdx=(-1/2)xcos2x+(1/4)sin2x+C2）∫xlnxdx=(1/2)∫lnxdx^2=(1/2)x^2lnx-(1/2)∫xdx=(1/2)x^2lnx-(1/4)x^2+C3）∫arccosxdx=xarccosx-...