2x^3y-1/2y^4-5xy^3+x^2y^2+1按x的升幂排列 2x^2-3x-4x^3按x的降次幂排列

x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) 计算：（1）8x^2y^2*(-3x/4y^5) (2)(x+y)^2/xy-y^2*(y-x)^2/xy+y^2 4xy-[(x²+5xy-y²)-(3xy-1/2y)]x=3,y=-6 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 已知1/x+1/y=5,求x+y+3xy/2x-4xy+2y的值,已知1/x+1/y=5,x+y+3xy/2x-4xy+2y的值, 5xy平方-2x平方y+[3xy平方-(4xy-2x平方y-2x平方y)],其中x=-2,y=-1求值 x^3y(-4y)^2+(-7xy)^2*(-xy)-5xy^3*(-3x)^2 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2) 已知2/x-1/y=3,则(2y-x+4xy)/(3x-6y-5xy)=? 若1/X-1/Y=3,求5X+2XY-5Y/X-4XY-Y 若1/x-1/y=3,求5x+2xy-5y/x-4xy-y的值 已知1/X-1/Y=5 ,则x-2xy-y/4x+3xy-4y XY(XY+3)+(XY+4)+4(X+Y+1)-(X+Y+2)