x/(x^2-x-2) dx 的微积分

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x/(x^2-x-2) dx 的微积分
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x/(x^2-x-2) dx 的微积分
x/(x^2-x-2) dx 的微积分

x/(x^2-x-2) dx 的微积分
是求∫[x/(x^2-x-2)]dx吧! 若是这样,则方法如下:
∫[x/(x^2-x-2)]dx
=∫{x/[(x-2)(x+1)]}dx
=(1/3)∫{[(x+1)-(x-2)]/[(x-2)(x+1)]}dx
=(1/3)∫[1/(x-2)]dx-(1/3)∫[1/(x+1)]dx
=(1/3)ln|x-2|-(1/3)ln|x+1|+C.

把1/(x^2-x-2)拆开为[(1/X-2)-(1/X+1)]/3,分成2个积分相减再去做就可以了

x/(x^2-x-2)=x/[(x-2)(x+1)]=x/[3(x-2)] - x/[3(x+1)] = [x-2+2]/[3(x-2)] - [x+1-1]/[3(x+1)]
=1/3 + (2/3)*1/(x-2) - 1/3 + (1/3)*1/(x+1)
= (2/3)*1/(x-2) + (1/3)*1/(x+1),
Sxdx/(x^2-x-2) = (2/3)*Sdx/(x-2) + (1/3)*Sdx/(x+1)
=(2/3) ln|x-2| + (1/3) ln|x+1| + C
其中, S表示积分符号, C为任意常数.