> with(linalg):
Warning, the protected names norm and trace have been redefined and
unprotected

> K:=42*matrix(3,3,[432,-297,54,  -297,432,-189,  54,-189,148]); 

                            [ 432    -297      54]
                            [                    ]
                    K := 42 [-297     432    -189]
                            [                    ]
                            [  54    -189     148]

> M:=matrix(3,3,[648,-81,-36,  -81,648,99,  -36,99,128]);  

                            [648    -81    -36]
                            [                 ]
                       M := [-81    648     99]
                            [                 ]
                            [-36     99    128]

> det(K-Omega*M);

                                                      2
  291654820800 - 133327918080 Omega + 6249746160 Omega

                         3
         - 46294416 Omega

> fsolve(det(K-Omega*M)=0,Omega);

                2.467738163, 23.39125451, 109.1410073

> map(sqrt, [%]);
> 
> 

               [1.570903614, 4.836450611, 10.44705735]

> 
