两边同乘以(x-1)(x+1)(x+2) :x(x+1)(x+2)-(x-1)(x+1)(x+2)=3(x-1)
(x+1)(x+2)=3x-3
x^2+3x+2=3x-3
x^2=-5
x1=√5i x2=-√5i(经检验是有意义的)