不定积分,最后两步回代怎么带的?

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2025-04-27 00:36:34
推荐回答(1个)
回答1:

x=sint,则 t=arcsinx,
sin2t=2sintcost
=2sint √(1 - sin²t)
=2x√(1 - x²),
cos2t=1 - 2sin²t
=1 - 2x²