若1/x+1/y=3,则2x-xy+2y/x-2xy+y的值是多少?还有已知x/y=2/7,求x²-3xy+2y²/2x²-3xy+2y&s后面这个应该是已知x/y=2/7，求x²-3xy+2y²/2x²-3xy+2y²

若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y 若1/x+1/y=2,则(2x-xy+2y)÷(3x+5xy+3y) 若1/X-1/Y=3,则2X+XY-2Y/X-2XY-Y=? 若1/x-1/y=2,则（3x+xy-3y)/(x-xy-y）的值为? 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( ） 若x^2-3x=1,则x^2y-3xy-y 若实数x,y满足1/x-1/y=5,则分式3x-2xy-3y/x+xy-y的值等于? 若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= 已知1/x=1/y=6,则3x-2xy+3y/3xy+x+y=?已知1/x+1/y=6,则3x-2xy+3y/3xy+x+y=? 若x-y=1,xy=5,则x^2y-xy^2＝ 若x/1-y/1=5,则x-2xy-y/2x+5xy-2y=? 若(2x-14xy-2y)除以(x-2xy-y)=4,则1/x-1/y= 若1/x-1/y=1/3,求(2x+3xy-2y)/(x-3xy-y) 若1/x-1/y=3,求(2x+3xy-2y)/(x-2xy-y)的值 若1/x -1/y =3,求(2x+3xy-2y)/(x-y-2xy)