7/(x^2+x)+4/(x^2-x)=6/(x^2-1)
7/[x(x+1)]+4/[x(x-1)]=6/[(x+1)(x-1)]
7(x-1)/x+4(x+1)/x=6
7x-7+4x+4=6x
5x=3
x=3/5