计算（x³-x+1）/（x²-1）-（x²+x）/(x-1)+(2x+3)/(x+1)计算（x+2y)/(x²-y²）+（y-2x）/（y²-x²）

计算（x³-x+1）/（x²-1）-（x²+x）/(x-1)+(2x+3)/(x+1)计算（x+2y)/(x²-y²）+（y-2x）/（y²-x²）
计算（x³-x+1）/（x²-1）-（x²+x）/(x-1)+(2x+3)/(x+1)
计算（x+2y)/(x²-y²）+（y-2x）/（y²-x²）

计算（x³-x+1）/（x²-1）-（x²+x）/(x-1)+(2x+3)/(x+1)计算（x+2y)/(x²-y²）+（y-2x）/（y²-x²）
1、原式可先直接通分,因为x^2-1=(x+1)(x-1),所以可以得到.
[（x^3-x+1）-(x^2+x)(x+1)+(2x+3)(x-1)]/(x^2-1)
在算出分子=-x-2 分数成了（-x-2）/(x^2-1)=(x+2)/(1-x^2)
2、(x+2y)/(x^2-y^2)+[(y-2x)/-(x^2-y^2)]
=[(x+2y)-(y-2x)]/(x^2-y^2)
=(3x+y)/(x^2-y^2)