已知方程2x-3y+4z-10=0,3x+2y-5z-15=0,则x-8y+13z=( )
已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z
已知x,y,z,同时满足方程x+3y-5z=0,2x-y-3z=0求x:y:z的值
已知,方程组:4x-3y-7z=0 x+2y=10z 则(x-y+z)÷(x+y+z)=——
已知{x-3y+2z=0 3x-3y-4z+0,则x:y:z=?
已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3
已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z均不为0,求3x*x+2y*y+5z*z/5x*x+y*y-
已知x+2y-4z=0,3x-y-z=0,则3x+2y+z/x+2y+z=
已知x-y+z=0,3x+y-5z=0,则x+y+z/x+2y-3z=?
已知4x-3y+z=0,x+2y-8z=0,xyz不等于0,求x+y-z/x-y+2z的值
已知方程组4x-y+3z=0 2x+y+6z=0且xyz不等于0,则x/y+y/z+z/x是多少
已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值
已知{3x+4y+5z=0,2x+3y-4z=0,求x+y+z/x-y+z的值.