两边乘(x+1)(x-1)
(4+x)(x-1)-5(x+1)(x-1)=2x(x+1)
x²+3x-4-5x²+5=2x²+2x
6x²-x-1=0
(3x+1)(2x-1)=0
x=-1/3,x=1/2
经检验,x=-1/3和x=1/2是方程的解