x+x+y+y+y+y=80 x+x+y+y=40 问XY=?

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 {(x,y) |x|+|y| x>y?x:y 化简 x / y(x+y) - y / x(x+y) = x(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? x^/y-x-y^/y-x化简. 化简x(y-x)-y(x-y) 行列式计算 x y x+y y x+y x x+y x y|x y x+y ||y x+y x ||x+y x y | y/(x+y)-x/(x-y) y=x(x x+x+x+x+y+y+y=56 X*Y,当Y x y x+yy x+y xx+y x y (3x-y)(3y+x)-(x-y)(x+y) 化简x/y(x+y)-y/x(x+y) 化简:(x+ y)(x-y) +(x+ y) +(x-y)