Question

Find -3A+6B A=[-3 5 -6] [9 -5 3] B=[-2 6 7] [2 -1 -6]

Answer 1

$A=\left[\begin{array}{ccc}-3&5&-6\\9&-5&3\end{array}\right];\ B=\left[\begin{array}{ccc}-2&6&7\\2&-1&-6\end{array}\right]\\\\-3A=\left[\begin{array}{ccc}(-3)(3)&(5)(3)&(-6)(3)\\(9)(3)&(-5)(3)&(3)(3)\end{array}\right]=\left[\begin{array}{ccc}-9&15&-18\\27&-15&9\end{array}\right] \\\\6B=\left[\begin{array}{ccc}(-2)(6)&(6)(6)&(7)(6)\\(2)(6)&(-1)(6)&(-6)(6)\end{array}\right]=\left[\begin{array}{ccc}-12&36&42\\12&-6&-36\end{array}\right]$

$-3A+6B=\left[\begin{array}{ccc}-9+(-12)&15+36&-18+42\\27+12&-15+(-6)&9+(-36)\end{array}\right]\\\\-3A+6B=\left[\begin{array}{ccc}-21&51&24\\39&-21&-27\end{array}\right]$