3/1-x²= 2/1+2x+x²- 5/1-2x+x²用换元法解

3/1-x²= 2/1+2x+x²- 5/1-2x+x²用换元法解

3/(1-x)(1+x)=2/(1+x)²-5/(1-x)²
两边乘以(1-x)²(1+x)²得
3(1-x²)=2(1-2x+x²)-5(1+2x+x²)
3-3x²=2-4x+2x²-5-10x-5x²
14x=-6
∴x=-3/7
检验：x=-3/7是方程的解