7y+120=5xy=?x=?x+y=?

|x|/x+y/|y|+xy/|xy|= 1/x-1/y=x,求5y+xy-5y/y-xy-x=? 已知x-y=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y) 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=? 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=? 6（x-y)-7(xy)=21,2(x-y)-5(x+y)=-1 化简:(x+y-4xy/x+y)*(x-y-4xy/x-y)= 证明|xy|=|x||y| xy-(x+y)=1000 证明|xy|=|x||y| 2x^+xy-y^-4x+5y-6=? 已知(1/x)-(1/y)=5,求(6x+7xy-6y)/(8y-9xy-8y) 已知:x-y=7,xy=5,则3xy-7x-7y=? 已知x-y=5,xy=3,则3xy-7x+7y=? x-y=5,xy=3,则3xy-7x+7y= {y-2x/xy=5,5y+7x/xy=22} 已知xy^2=-2求xy（2x^3y^7+5x^2y 已知实数x,y,xy=5,x+y=7,求代数式x²y+xy²的值