用配方法化二次型f(x,y,z) = x²+2xy+4xz+4yz+7y²-2z²化为标准
已知4x-5y+2z=0,x+4y-3z=0,求(x²+y²+z²)/xy+yz+xz
(2X+Z-Y)/(X^2-XY+XZ-YZ)-(Y-Z)/(X^2-XY-XZ+YZ)
已知x/3=y/4=z/6,求(xy+yz+xz)/(x²+y²+z²)
已知x+y+z=1,x²+y²+z²=2求xy+yz+xz的值
x/3=y/2=z/5,求xy+yz+xz/x²+y²+z²
x^2+y^2+xy=25/4,x^2+z^2+xz=169/4,y^2+z^2+yz=36,求xy+xz+yz
已知2x-3y-z=0,x+3y-14z=0,且x,y,z不为0.求4x的二次幂-5xy+z的二次幂/xy+yz+xz的
求(2X+Z-Y)/(X^2-XY+XZ-YZ)-(2X+Y+Z)/(X^2+XY+XZ+YZ)
化简(2x-y-z/x^2-xy-xz+yz)+(2y-x-z/y^2-xy-yz+xz)+(2x-x-y/z^2-xz
已知x^3+y^3-z^3=96,xyz=4,x^2+y^2+z^2-xy+xz+yz=12,则x+y-z等于
1.已知3x-4y-z=0,2x+y-8z=0.求x²+y²+z²/xy+yz+2xz 的
若x/3=y=z/4,且xy+xz+yz=76,求2x*x+12y*y+9z*z的值