題組內容

二、所有題目請敘述計算過程,無計算過程不給分
(1). Let A = $\begin{bmatrix} 1 & 2 & 2 \\ 2 & 1 & 2 \\ 2 & 2 & 1 \end{bmatrix}$

(a) Write down the characteristic polynomial of \( A \) and use it to find the eigenvalues. (5%)