7/(x^2+x)+4/(x^2-x)=6/(x^2-1)
可以化简
7/x(x+1)+4/x(x-1)=6/(x+1)(x-1)
等式两边同时乘以x(x+1)(x-1)
7(x-1)+4(x+1)=6x
化简 5x=3 x=3/5