How to solve a matrix quadratic equation?

How can I solve this kind of determinant equation? Here is the example:

det(K-w²*M)=0

Where I know de matrix K (3x3) and M (3x3), and have to find the vector w.

Waiting to your reply, thank you in advance!

Answer 1

[Ajay Kumar]

Kminusw2 = K - w^2;
mymatrix = Kminusw2.*M;
myfinalanswer = det(mymatrix);

Answer 2

[Alex Mcaulley]

syms w
solve(det(K-w^2*M),w)