Question

The eigen values of the following matrix $\left[\begin{array}{cc}10& -4\\ 18& -12\end{array}\right]$ are

• A. 4, 9
• B. 6, -8
• C. 4, 8
• D. -6, 8

Answer 1

The correct option is B 6, -8

C.equation is $|A-\lambda I|=0$
$\left|\begin{array}{cc}10-\lambda & -4\\ 18& -12-\lambda \end{array}\right|=0$
${\lambda }^2-(-2)\lambda +(-120+72)=0$
${\lambda }^2+2\lambda -48=0$
$\lambda =6,-8$