化简求值:【(x+2分之x)-(x-1分之x-2)】除以(x-4分之x^2-4x+4)其中x=-1

=[x(x-1)-(x+2)(x-2)]/(x+2)(x-1)×(x-2)²/(x-4)
=-(x-4)/(x+2)(x-1)×(x-2)²/(x-4)
=-(x-2)²/(x+2)(x-1))
当x=-1时
原式=-9/(-2)
=9/2