已知x+y+2(-x-y+1)=3(1-y-z)-4(y+x-1),则x+y的值是
已知x::y:z=3:4:5,(1)求x+y分之z的值;(2)若x+y+z=6,求x,y,z.
已知变量x,y满足约束条件 y≤2 x+y≥1 x-y≤1 则z=3x+y的最大值是
已知{x:y:z=1:2:3,x+y+z=12,求x、y、z的值
(1)已知3x=2y=z,求2x+y-z分之x-y+2z的值.(2)若(x+y):(3x-2y)=5:2,则x:y=?
已知X、Y、Z满足2X-Y+4Z=8(1);X-2Y-Z=7(2)求X-Y-Z的值
1 已知想x,y,z满足2x-y+4z=8,x-2y-z=7,求x-y+z的值
已知:3x-2y/4=38-2x/6=3y-2z,求1/3(x+y+z):(9x-6y)的值
已知实数x,y满足{x≧0 y≧x 4x+3y≦12}.z=2y+3/x+1 的取值范围
已知x/2=y/3=z/4,求下列各式 (1)(x+y+z)/x (2)(x-y+2x/(x-y-2z)
分解因式:(1):x(x-y)+y(y-X) 多项式(x+y-z)(x-y+z)-(y+z-X)(Z-x-y)的公因式是
已知实数xyz满足x/y+z+y/z+x+z/x+y=1求x^2/y+z+y^2/z+x+z^2/x+y的值
已知1/x-1/y=1/x-y则2y/x+2x/y的值是