1/x+1/y=4,则（3x+xy+3y）/（x-xy+3y)=

若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 已知x+y=3,xy=1,则4x+3xy+4y= 1/x+1/y=4,则（3x+xy+3y）/（x-xy+3y)= 已知1/X-1/Y=5 ,则x-2xy-y/4x+3xy-4y 已知2/x-1/y=3,则(2y-x+4xy)/(3x-6y-5xy)=? 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 x-y=1,xy=2.求：(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 .已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 化简求值x-4y/2x-7xy+3y×x-2xy-3y/2x+3xy-2y÷3x-6y/4x-4xy+y,其中：x=1999,y=-1 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=( ） 已知x-y=3,xy=1,求（-2x+2x+3y)-(3xy+2y-2x)-(x+4y+xy) 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 已知x-y=1,则x^4-x^3y-xy^3-3x^2y+3xy^2+y^4= 已知(x-y)/(x+y)=-1/2,则分式(x²+4xy+3y²)/(x²+2xy-3y²)的值等于 实数x,y满足x^3-y^3-3xy=1,则x-y= |x-3y-1|+(x+y)^2=4xy求y分之x