•First 2×2 Example

In[1]:=

A = (3 1) ; 1 3

In[2]:=

p[λ_] = Det[A - λ I _ 2]

Out[2]=

8 - 6 λ + λ^2

In[3]:=

Factor[p[λ]]

Out[3]=

(-4 + λ) (-2 + λ)

In[4]:=

Solve[p[λ] == 0, λ]

Out[4]=

{{λ -> 2}, {λ -> 4}}

Converted by Mathematica  (November 21, 2002)