若【x+y=5,2x+y=8】,则x+2y=

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 若【x+y=5,2x+y=8】,则x+2y= 若x^2-y^2=40,(x+y)=8/5,则x-y= 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 若f(x+y,y/x)=x^2-y^2,则F(X,Y)= 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 若2x=3y,则(x*x+y*y)/x*x=? 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 若x-y不等于0,2x-3y=0,则分式(10x-11y)/(x-y)的值是（）?(10x-11y)/(x-y) =[(8x-8y)+(2x-3y)]/(x-y) =8为什么8X-8Y=8？(10x-11y)/(x-y)=[(8x-8y)+(2x-3y)]/(x-y)=8+(2x-3y)]/(x-y)=8+0=8 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若(X×X+Y×Y)(X×X+Y×Y-5)=36,则X×X+Y×Y＝ 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 若2x-5y=0,则y：x 若5x+3y=3x+4y=x+2y+6,则x+y=___ 若x^2+y^2-6x+8y+25=0 则y/x-x/y的值是 若X+Y=8,(X-Y)^2=4,则X^2+Y^2= 若|x+y-3|+(x-y-5)^2=0,则x)^2-y^2=