不定积分习题 ∫sinxcos2xdx ∫x (x-1)^1⼀2dx 谁知道这么做啊

2024-11-28 08:27:37
推荐回答(1个)
回答(1):

∫sinxcos2xdx
=∫sinx(2cos²x-1)dx
=-∫(2cos²x-1)d(cosx)
=-(2/3)cos³x+cosx+C

∫x (x-1)^1/2dx
令(x-1)^1/2=u,x=u²+1,dx=2udu
=∫(u²+1)u*2udu
=2∫(u^4+u²)du
=(2/5)u^5+(2/3)u³+C
=(2/5)(x-1)^(5/2)+(2/3)(x-1)^(3/2)+C