已知x-y=5,xy=3,则3xy-7x+7x=____________a 抱歉已知x-y=5，xy=3，则3xy-7x+7y=____________

已知x-y=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y) 已知x-y=5,xy=3,则3xy-7x+7y=? 已知:x-y=7,xy=5,则3xy-7x-7y=? 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 已知xy/x+y=3,则代数式2x-7xy+2y/-x+xy-y的值是多少? 3xy+xy+3+4xy-7化简,已知x=5,y=6 已知x+y=5,xy=-3,则x^2y+xy^2, 已知xy^2=-2求xy（2x^3y^7+5x^2y 已知（X+Y-3）²+|5+XY|=0,则X-XY+Y 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：x²-xy=9,xy-y²=5,则x²-2xy+y²=（）,3x²+xy-2y²+（） 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^2=-2xy(x^2y^5-xy^3-y) 已知x-y=4,xy=7,则代数式(4x-5y+3xy)-(3x-4y)+7xy的值是?