# Determine all possible real a, so that matrix #((1,a,a),(a,1,a),(a,a,1))# has 3 positive real eigen value ?

##### 1 Answer

Apr 10, 2017

See below.

#### Explanation:

Giving

so this polynomial has three real roots or

with eigenvalues

This result does not surprise us because

NOTE:

Positive eigenvalues are obtained for