Answer:
5A+10B=
[tex]5\left[\begin{array}{ccc}2&8&-4\\4&-6&0\end{array}\right] +10\left[\begin{array}{ccc}-9&5&6\\3&3&12\end{array}\right] \\=\left[\begin{array}{ccc}10&40&-20\\20&-30&0 \end{array}\right] +\left[\begin{array}{ccc}-90&50&60\\30&30&120\end{array}\right] \\=\left[\begin{array}{ccc}10-90&40+50&-20+60\\20+30&-30+30&0+120\end{array}\right] \\=\left[\begin{array}{ccc}-80&90&40\\50&0&120\end{array}\right][/tex]
Step-by-step explanation:
5(A+2B)=5A+10 B
