已知x-y=5,xy=3,则3xy-7x+7y=______.
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都是正实数,且x+y-3xy+5=0,则xy的最小值______.
已知x+y=4,xy=2,则x2+y2+3xy=______.
已知xy^2=-2求xy(2x^3y^7+5x^2y
已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y=
已知x+y=3,xy=1,求代数式5xy+4x+7y+6x-3xy-4xy+3y的值.
已知X+Y=6,xy=3求代数式(5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)的值
已知:(2x+3y-4)2+|x+3y-7|=0,则xy=______.
已知x-y=4xy,则2x+3xy-2yx-2xy-y
已知 x-3*根号(xy)-4y=0,则 [2x+3*根号(xy)-2y]/[3x-根号(xy)+y]=______
已知x+y=5,xy=-3,则x^2y+xy^2,