x y=50 3x=2y 怎么求?

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-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 2Y：30%=3X：50%求X:Y x+y=50 3x=2y 怎么求 x y=50 3x=2y 怎么求? 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y y=3(x-y),x=2(x-y)求x,y的值 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 y=2x+50/x的最小值怎么求 已知:3x-5y=0,求x/y,x-y/y,x-y/x 曲线y=x^3+x-2导数怎么求 y=(x-3)/(x-2)的值域怎么求 推倒公式:(x+y)(x*x-3x+y*y)=x*x*x+y*y*y怎么做. {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? x+y/2+ x-y/2=6 2(x+y)-3x+3y=24 求X Y 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y