小明在做化简求值题：（xy-x²）÷xy分之x²-2xy+y²乘x²分之x-y

小明在做化简求值题：（xy-x²）÷xy分之x²-2xy+y²乘x²分之x-y 计算：（xy-x²）乘 x-y分之xy 化简求值(xy-x²)/xy分之x²-2xy+y²乘x²分之x-y,其中y=二分 先化简,再求值:2x²-2y²分之4x²-8xy+4y²乘xy(x-y)分之(x （xy-x²）除以xy分之x²-2xy+y²乘以x²分之x-y x²+y²+2xy分之x²-4y² ÷x²+xy分之2y+x (x²+2xy+y²分之x²-4y²)÷(x²+xy分之x+2y) 先化简,再求值,x分之x-y÷（x-x分之2xy-y²）其中x=2,y=-1 化简求值.（x-2y分之4xy 再加+x)除以4x³-x²y分之x²+4xy+4y (xy分之x²-y²)-(xy-x²分之xy-y²) (1)（xy-x²)除以xy分之x²+y²-2xy 乘 x²分之x-y (2)先 （xy-x²）·x²分之x-y