행렬의 덧셈

$A + 2 B$$\displaystyle = \left( \begin{array}{lll} \begin{array}{rrr} 2 & & 0 \\ 3 & & - 1 \end{array} \end{array} \right) + 2 \left( \begin{array}{lll} \begin{array}{rrr} 1 & & 2 \\ 0 & & 2 \end{array} \end{array} \right)$ $\displaystyle = \left( \begin{array}{lll} \begin{array}{rrr} 2 & & 0 \\ 3 & & - 1 \end{array} \end{array} \right) + \left( \begin{array}{lll} \begin{array}{rrr} 2 & & 4 \\ 0 & & 4 \end{array} \end{array} \right)$ $\displaystyle = \left( \begin{array}{lll} \begin{matrix} 2 + 2 & & 0 + 4 \\ 3 + 0 & & - 1 + 4 \end{matrix} \end{array} \right) = \left( \begin{array}{lll} \begin{array}{rrr} 4 & & 4 \\ 3 & & 3 \end{array} \end{array} \right)$ 이므로 구하는 모든 성분의 합은 $4 + 4 + 3 + 3 = 14$