原式=[(x-1)²/(x-2)²(x+1)²]÷[-(x-1)²/(x-2)]÷[1/x²(x+2)²]
=-(x-1)²(x-2)x²(x+2)²/[(x-2)²(x+1)²(x-1)²]
=-x²(x+2)²/[(x-2)(x+1)²]