0.1x+0.3y = 0.15(x+y) 0.1x+0.3y+0.2×300 = 0.18×(x+y+300) x=?

二元函数f(x,y)=x+y/x-y,求f(y/x,x/y) [x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 x+y=5; x^y+y^x=17 因式分解下列式子：x(x-y)+y(y-x)=? 根据x+x+x+y+y=54,x+x+y+y+y=56,求出x.y的值 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) ) y=cos(x-y) (x+y-z)(x-y+z)= (x-y)(x+y)(xx-yy)=? y'-2y=(e^x)-x y'+2y/x=x通解