高数,不定积分到一道题,这是怎么算出来的?求助大神~

2025-01-09 04:46:28
推荐回答(1个)
回答1:

let
2x-1= 2sint
2dx= 2cost dt
dx = cost dt

∫√[4-(2x-1)^2] dx
=4∫ (cost)^2 dt
=2∫ (1+cos2t) dt
=2 [ t + (1/2)sin2t ] + C
=2{ arcsin[(2x-1)/2] + (1/4)√[4-(2x-1)^2] } + C

where
t= arcsin[(2x-1)/2]
sin2t
= 2sint.cost
=2 [(2x-1)/2]. [√[4-(2x-1)^2] /2]