已知x+y=-7,xy=14,求5（0.5xy+2一）+（6x-（2xy-y-5x））的值已知x+y=-7，xy=14，求5（1/2xy+2y）+（6x-（2xy-y-5x))d的值。是=20吗

已知xy^2=-2求xy（2x^3y^7+5x^2y 已知(1/x)-(1/y)=5,求(6x+7xy-6y)/(8y-9xy-8y) 已知X+Y=6,xy=3求代数式（5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)的值 已知x+y=3,xy=1,求代数式5xy+4x+7y+6x-3xy-4xy+3y的值. 已知实数x,y,xy=5,x+y=7,求代数式x²y+xy²的值 已知x+y=-5,xy=7,求x^2y+xy^2-x-y的值 已知1/x-1/y=5,求分式y+xy-x/2x+7xy-2y的值. 已知1/x-1/y=5 求分式-x+xy+y/2x+7xy-2y 已知1/X-1/y=5,求分式(y+xy-x)/(2x+7xy-2y)的值 已知xy^2=-2,求-xy（x^2y^5-xy^3-y)的值. 已知xy^2=-2 求-xy(x^2y^5-xy^3-y) 已知xy平方=-2,求-xy(x^3y^7-3x^3y^7-y)刚刚发现打错题了，应该是：已知xy平方=-2,求-xy(x^3y^7-3x^2y^5-y) 已知xy/x+y=3,求代数式3x-5xy+3y/-x+3xy-y的值.已知xy/x+y=3,求代数式3x-5xy+3y/-x+3xy-y的值. 已知X+y=6,xy=7 求x^2y+xy^2=已知X+y=6,xy=7 x^2y+xy^2 已知：x+xy=14,y+xy+x=28.求x+y的值. 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2 已知x^-xy=5,xy-y^=-3,求式子3(x^-xy)-xy+y^的值 已知xy^2=-2求xy（2x^3y^7+5x^2y^5-y)的值