2/(x^2+x)+3/(x^2-x)=4/(x^2-1),2/[x(x+1)]+3/[x(x-1)]=4/[(x+1)(x-1)],方程两边同乘以最简公分母：x(x+1)(x-1),得：2(x-1)+3(x+1)=4x,2x-2+3x+3=4x,2x+3x-4x=2-3,x=-1.检验：当x=1时,最简公分母：x(x+1)(x-1)]=0,所...