已知x=y=5,x-y=7.求x^2-y^2,xy,x^2+y^2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:3x-5y=0,求x/y,x-y/y,x-y/x 已知：4x = 5y,求(x+y) ：y 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+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-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 已知x+y=-5,x*x+y*y=19求xy和（x-y)*(x-y)的值 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 已知2/x+2/y=根号24,求 x/y(x-y) - y/x(x-y)的值 已知2/x 2/y=根号24,求 x/y(x-y) - y/x(x-y)的值 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知2/y-5/x=16,5/y+6/x=13,求x、y. 已知x+y=-6,x-y=5,求x^2-y^2