✔ 最佳答案
Sol
x^2+2x+2=(x+1)^2+1
Set x+1=Tanw
w=ArcTan(x+1)
SinwCosw=(x+1)/(x^2+2x+2)
x^2+2x+2=sec^2 w
dx=Sec^2 wdw
∫-4dx/(x^2+2x+2)^2
=∫-4Sec^2 w/sec^4 w
=∫-4Cos^2 wdw
=∫-2(1+Cos2w)dw
=-2∫dw-∫Cos2wd(2w)
=-2w+Sin(2w)+c
=-2ArcTan(x+1)+2(x+1)/(x^2+2x+2)+c