7/(x²+x)+3/(x²-x)=6/(x²-1)
7/x(x+1)+3/x(x-1)=6/(x+1)(x-1)
两边同乘x(x+1)(x-1)
7(x-1)+3(x+1)=6x
7x-7+3x+3=6x
4x=4
x=1