若x≥0,y≥0,2x+y=6z=4x^2+3xy+y^2-6x-3y的最大值和最小值（较详细解答过程）

若4x-3y-6z=0,x+2y-7z=0,则x+y+z/3x-y+z=? 已知：x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值. x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值 已知x、y、z满足方程组：x+y-z=6；y+z-x=2；z+x-y=0 求x、y、z的值 已知X.Y.Z满足方程组,X+y-Z=6y+z-x=2z+x-y=0求X.Y.Z的值 若x≥0,y≥0,且2x+3y≤100,2x+y≤60,求z=6x+4y的最大值? x+y+z=4x-5y=y-x+6z,xyz不等0,x:y:z=? 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 已知xyz≥0,x+y+z=1,化简x（2y-z）/(1+x+3y)+y(2z-x) /(1+y+3z) +z(2x-y)/(1+z+3x) 若（z-x)的平方-4(x-y)(y-z)=0试确定x-2y+z若（z-x)^2-4(x-y)(y-z)=0试确定x-2y+z 三元一次方程x+y+z=0 4x+2y+z=3 9x+3y+z=6x+y+z=04x+2y+z=3 9x+3y+z=6 若（z-x）^2-4(x-y)(y-z)=0,试说明:x-2y+z=0 若(z-x)的二次方-4(x-y)(y-z)=0,求证x-2y+z=0 {x+y+z=0 {4x+2y+z=3 {9x+2y+z=6 X+y-z=6;x-3y+2z=0;3x+2y-z=4 若(z-x)^2-4（x-y）（y-Z)=0,试说明x-2y+z=0. {x+y+z=0 4x+2y+z=3 9x+3y+z=6 若x/2=y/3=z/4不等于0,求x+y+z/x+y-z的值