已知x,y,z均为实数,且满足:x+2y-z=6,x-y+2z=3.求x+y+z的最小值

已知x,y,z均为实数,且满足:x+2y-z=6,x-y+2z=3.求x+y+z的最小值 已知x.y.z均为实数且满足x+y+z=4.求xy+yz+xz的最大值. 已知x,y,z均为实数,a>0,且满足x+y+z=a,x^2+y^2+y^2=1/2a^2,求x,y,z的取值范围已知x,y,z均为实数,a>0,且满足x+y+z=a,x^2+y^2+y^2=1/2×a^2,求x,y,z的取值范围 已知x,y,z为非零实数,且满足x+y-z/z=y+z-x/x=z+x-y/y 求x+y+z/z的值 x+y+z=a,x^2+y^2+z^2=1/2a^2,求x,y,z取值范围已知x,y,z均为实数,a>0,且满足x+y+z=a,x^2+y^2+z^2=1/2 a^2,求x,y,z的取值范围. 已知实数X,Y,Z,满足X^2-2X+Y=Z-1,且X+Y^2+1=0,试比较X,Y,Z的大小. 已知x,y,z为实数,且满足x+2y-5z-3=0;x-2y-z+5=0,则x+y+z的最小值为多少? 已知x,y,z为实数,且满足x+2y-z=6,x-y+2z=3,则x^2+y^2+z^2的最小值? 已知x,y,z 为实数,且满足 x+2y-z=6 x-y+2z=3, 求 x^2+y^2+z^2的最小值. 已知x、y、z为实数,且满足｛x+2y-z =6 x-y+2z=3,求x^2+y^2+z^2的最小值 已知x,y,z为3个非负实数,且满足3x+2y+z=5,x+y-z=2,若s=2x+y-z求s的取值范围 已知x、y、z为实数,且满足x+2y-5z=-7,x-y+z=2,试比较x方-y方与z方的大小关系 已知x,y,z为实数且满足x+2y-5z=3 ,x-2y-z=-5 则x方+y方+z方的最小值是 已知x,y,z,为非负实数,且满足x+y+z=30,3x+y-z=50 求 u=5x+4y+2z的最大值和最小值 已知x,y,z,为非负实数,且满足x+y+z=30,3x+y-z=50 求 u=5x+4y+2z的最大值和最小值 已知x,y,z为正实数,满足x-y+2z=0,求y²/(xz)的最小值 已知X Y Z为正实数,且不全相等,求证X^2/Y+Y^2/Z+Z^2/X>X+Y+Z 已知x,y,z均不为0,且满足方程组{x+y-z=0,①2x-y-5z=0.②试求(2x+y+3z)/(3x-y-z)值.