x+y=45,24x+18y=960

解方程组24/(x+y) +24/(x-y) = 7/3 ,8/(x+y) +18/(x-y) = 4/3 2(x+y) 3x+3y=24 x+y/2x x y/2y= 1 已知2/x+2/y=根号24,求 x/y(x-y) - y/x(x-y)的值 已知2/x 2/y=根号24,求 x/y(x-y) - y/x(x-y)的值 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)=? 若x、y、z满足2x+3y+z=18,4x-3y+5y=24,求x+3y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