# coding: utf-8

# In[2]:

import sympy as sp
sp.init_printing()


# In[3]:

eps = sp.Symbol("epsilon")
lam = sp.Symbol("lambda")


# In[4]:

m = sp.Matrix([[1, eps], [eps, 1]])
m


# In[5]:

m.charpoly(lam)


# Observe the occurrence of $(1-\epsilon^2)$ above.