已知x-y=1,x^2+y^2=25,求xy的值请说一下过程。。

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 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? 已知实数x,y满足(x+y)^2=1,(x-y)^2=25,求x,y的值 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知x求^2+y^2-6x-8y+25=0求1/x-y /x+y/x^4-y^4 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x²-y²-1/2x+y 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷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|=2,|y|=3,|x+y|=-(x+y)求x-y 已知x≠y,x^2-x=y^2-y,求x+y的值. 已知 x-2y=-2 求(2y-x)平方-2x+4y-1 已知x平方+y平方+2xy+1=2x+2y,求x+y 已知x平方+y平方-2xy-2x-2y=-1,求x+y 已知3x-4y/2x+y=1/2 求x/y的值 已知x-2y/y+3x=1/2,求x/y的值