Question

Eigen values of the matrix $A=\left[\begin{array}{ccc}3& 1& 4\\ 0& 2& 6\\ 0& 0& 5\end{array}\right]$ are

• A. 2,3,5
• B. 1,2,3
• C. 1,2,5
• D. 3,5,8

Answer 1

The correct option is A 2,3,5

$|A-\lambda I|=0$

$\left|\begin{array}{ccc}3-\lambda & 1& 4\\ 0& 2-\lambda & 6\\ 0& 0& 5-\lambda \end{array}\right|=0$

$(3-\lambda )(2-\lambda )(5-\lambda )=0$
$\lambda =2,3,5$