谁能用两种方法求解大神

2025-04-05 03:39:40
推荐回答(1个)
回答1:

(1)设
x²/(x+2)³
=A/(x+2)+B/(x+2)²+C/(x+2)³
∴x²=A(x+2)²+B(x+2)+C
比较系数得到
A=1,B=-4,C=4
∴原式=∫1/(x+2)·dx-∫4/(x+2)²·dx
+∫4/(x+2)³·dx
=ln|x+2|+4/(x+2)-2/(x+2)²+C

(2)设u=x+2,则du=dx
原式=∫(u-2)²/u³·du
=∫(1/u-4/u²+4/u³)du
=ln|u|+4/u-2/u²+C
=ln|x+2|+4/(x+2)-2/(x+2)²+C