若(x+y)^2=11,（x-y)^2=7,则xy的值为________.

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x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 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 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x*x+y*y=x+y-1/2,求x,y的值如题 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2x=3y,则(x*x+y*y)/x*x=? 若3x-2y=15,3y-2x=11,求x+y 填空：x-y/x+y=( )/x^2-y^2 （x-y)2•(y-x)³(x-y)=? y+y'-2y=2x 微分方程y - 2y' + y = x (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一