设x/3=y/1=z/2=k
则x=3k y=k z=2k
代入 xy+yz+xz=99
3k^2+2k^2+6k^2=99
11k^2=99
k^2=9
x=3k y=k z=2k
代入 2x^2+12y^2+9z^2
=2(3k)^2+12k^2+9(2k)^2
=66k^2
=66*9
=594