求解一道不定积分的题目!谢谢啦!!!!!!!!

请写出步骤和思路!谢谢!
2024-11-22 06:03:06
推荐回答(2个)
回答1:

解:设t=arcsinx,则x=sint,dx=costdt
∴∫[arcsinx/(1-x^2)^(3/2)]dx=∫{tcost/[1-(sinx)^2]^(3/2)}dt
=∫[t/(cost)^2]dt
=∫t(sect)^2dt
=∫td(tant)
=ttant-∫tantdt
=ttant±ln(sect)+c
∴原式=arcsinxtan(arcsinx)±ln[sec(arcsinx)]+c
又∵tan(arcsinx)=sin(arcsinx)/cos(arcsinx)
=x/√[1-sin(arcsinx)^2]
=x/√(1-x^2)
又∵ln[(secarcsinx)]=-ln[cos(arcsinx)]
=-ln[1-sin(arcsinx)^2]^(1/2)
=-[ln(1-x^2)]/2
∴原式=[xarcsinx/√(1-x^2)]±[ln(1-x^2)]/2+c
={xarcsinx±[ln(1-x^2)]√(1-x^2)}/[2√(1-x^2)]+c

回答2:

标准的三角换元法! 令 x=sint,代入

=∫ t / (cos t)^2 dt =∫ t d tant (分部积分)

=t 乘 tan t + ln(cost) + C

= arcsinx乘x / 根号(1-x^2) + 1/2 乘 ln(1-x^2) +C