已知x-y=8 xy=7,则3xy-2x+2y+4(y-x)²=?

已知x-y=4xy，则2x+3xy-2yx-2xy-y 已知xy/x+y=2,则代数式3x-5y+8y/-x+3xy-y的值 已知x²-3xy+4x=3,y²+xy-4y+7=0,则xy-1/2(x²+y² 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 已知x-y=4xy,求x-2xy-y分之2x+3xy-2y的值! 已知：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 已知X/Y=2,则X²+2XY-3Y²/X²-XY+Y²=? 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)} 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知x+y=4,xy=2,求代数式2(3x+2xy)+(2xy+3x+2y)-(4xy-7y)的值 已知x=3y,试求(x-y)^2+2xy-y^2/x^2+7xy+y^2