若x+y=2,x^2+y^2=15,求xy的值若(x+y)^2=7,(x-y)^2=5,求xy的值

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 x^2+y^2=15,x+y=7,x＞y,求x-y 若x*x+y*y=x+y-1/2,求x,y的值如题 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 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3x-2y=15,3y-2x=11,求x+y 若x*x-4y*y=-15,x+2y=3,求x和y的值 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 x+2y=2x+y+1=7x-y 求：2x-y? f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! 如果|X|=4 |Y|=2 且|X+Y|=X+Y 求X+Y 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y f(x+y,y/x)=x^2-y^2求f(x,y) 已知x≠y,x^2-x=y^2-y,求x+y的值. f(x+y,y/x)=x^2-y^2,求f(x,y),详见里面