（19x-96y=5910  （30x-y=2340

已知x+y=-5,x*x+y*y=19求xy和（x-y)*(x-y)的值 x+x+x=15,x+y+y=19,求y-x等于几 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 ) 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)=? 已知x+y=-5,x*x*x+y*y=19,求xy和(x-y)的值 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) 求y'=y/(y-x)