原式=-2x+x^2-3-x^2+2x-1
=-4
原式=(y+2)(y-2)/(y-3)(y+2)+(y+2)/(y+1)
=(y-2)/(y-3)+(y+2)/(y+1)
=(y^2-y-2+y^2-y-6)/(y-3)(y+1)
=(2y^2-2y-8)/(y-3)(y+1)