x+y=5000.7x+0.9y=386解得x=310y=190

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 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 x*y'*sin(y/x)-y*sin(y/x)+x=0 求微分方程的解 解方程x*x+xy=y+y*y 已知实数x,y满足(x+y)平方=1,(x-y)平方=25,求x,y得值 ) y=cos(x-y) 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)