Question

Seja A=(aij) 3x3 definida por aij 21+j, se i=j

Answer 1

$A\;=\;\left[\begin{array}{ccc}a_{_{11}}&a_{_{12}}&a_{_{13}}\\a_{_{21}}&a_{_{22}}&a_{_{23}}\\a_{_{31}}&a_{_{32}}&a_{_{33}}\end{array}\right] \\\\\\A\;=\;\left[\begin{array}{ccc}2\,.\,1+1&2\,.\,1-2&2\,.\,1-3\\2\,.\,2-1&2\,.\,2+2&2\,.\,2-3\\2\,.\,3-1&2\,.\,3-2&2\,.\,3+3\end{array}\right]\\\\\\A\;=\;\left[\begin{array}{ccc}3&0&-1\\3&6&1\\5&4&9\end{array}\right]$