-(2xy-y^2+1/2x^2)-2(1/3xy+1/4y^2-x^2)

(x+y-2xy)(x+y-2)+(1-xy)² 计算3xy[2xy-x(y-2)+x-1] 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 已知：x-y=1,xy=-2.求：(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 x-y=1,xy=2.求：(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 .已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 xy(xy+1)+(xy+3)-2(x+y+2分之一）-(x+y-1)的平方 (-3分之1xy)的平方×[xy(2x-y)-2x(xy-y的平方)] 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 先化简,再求值 ⒈2(Xy+Xy)-3(Xy-xy)-4Xy,其中X=1,y=-1 5x^2y/-1/2xy*3xy^2 y^3+xy^2+2xy+x^2-1 因式分解