x+y=17 x+x+y+y+y+y=44问x和y各是多少

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 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=5; x^y+y^x=17 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 7x:4y,x:y=( ):( (x-4y)(2x+y)= 5x-4y(y-x)=? ：y' +y= cos x y= 微分方程y - 2y' + y = x 求y'=y/(y-x) y+y'-2y=2x x+x+x+x+y+y+y=56 D：y>=x,y y'/y=1/x {(x,y) |x|+|y|