=(x²+x-x)/(x+1)×(x+1)/(x+2)(x+1)×(x+2)(x-2)/x(x-2)
=x²/(x+1)×(x+1)/(x+2)(x+1)×(x+2)(x-2)/x(x-2)
=x/(x+1)
x=-1/2时
原式=-1/2/(-1/2+1)
=-1