由X/Y=2Y/X-Y 怎么解得x=2y?

由y=x^2+4\x^2+1得x^2=y+4\y+ 1 [x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 由二元一次方程组3X+2Y=9,2X+3Y=6,则得X+Y= ,X-Y=?. 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'-2y=(e^x)-x y'+2y/x=x通解 解微分方程y"+y'=x^2 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 数学题已知p=x^/x-y-y^/x-y,q=(x+y)^-2Y(X+Y), 将3x-y=7和2x+y=8组成方程组得，3x-y=72x+y=8，解得，