[(2x-x^2)(x^2+4x+3)]/[(x^2+x)(x^2-5x+6)]
=-x(x-2)/(x+3)(x+1)/x(x+2)(x-3)(x-2)
=-(x+3)(x+1)/(x+2)(x-3)
当x=2时
原式=-5×3/(-4)
=15/4谢谢。你还能告诉我[(a/a-2)-(a/a+2)]÷4a/2-a,其中a=-1/2。吗请采纳后，求助，好吗？一定帮你答