HP 48gII - Manual (Page 371)

Page 11-45
Using the variable
λ to represent eigenvalues, this characteristic polynomial is
to be interpreted as λ 3 -2 λ 2 -22 λ +21=0.
Function EGVL
Function EGVL (EiGenVaLues) produces the eigenvalues of a square matrix.
For example, the eigenvalues of the matrix shown below are calculated in
ALG mode using function EGVL:
The eigenvalues
λ = [ -√10, √10 ].
Note: In some cases, you may not be able to find an ‘exact’ solution to the
characteristic polynomial, and you will get an empty list as a result when
using Function EGVL. If that were to happen to you, change the calculation
mode to Approx in the CAS, and repeat the calculation.
For example, in exact mode, the following exercise produces an empty list as
the solution: