21/(x+y)+4/(x-y)=12/(x+y)+7/(x-y)
{(x,y) |x|+|y|
x>y?x:y
(x*x+y*y)(x*x+y*y)-(x*x+y*y)=12 求x*x+y*y等于多少
x(x-y)+4(y-x)因式分解
x-4y分之3x + 4y-x分之x+y - x*x-4y分之7y
1.x+x+x+y+y=6.4 y+y+y+x+x=7.1 x= ( ) y=( ) 2.1,4,7,10,13……这串
已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y除以2x-y
已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y/2x-y的值
已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值
已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y
x^2-y^2/x+y-4x(x-y)+y^2/2x-y,
二元函数f(x,y)=x+y/x-y,求f(y/x,x/y)