Chapter 2.4A, Problem 9MCQ

To determine

To find: $B-3A$ and if the matrix does not exist then write impossible.

Answer to Problem 9MCQ

  $\left[\begin{array}{ccc}\begin{array}{l}-11\\ 8\end{array}& \begin{array}{l}-7\\ -9\end{array}& \begin{array}{l}27\\ -2\end{array}\end{array}\right]$

Explanation of Solution

Given information:

  $\begin{array}{l}A=\left[\begin{array}{ccc}\begin{array}{l}3\\ -1\end{array}& \begin{array}{l}5\\ 0\end{array}& \begin{array}{l}-7\\ 4\end{array}\end{array}\right]\\ B=\left[\begin{array}{ccc}\begin{array}{l}-2\\ 5\end{array}& \begin{array}{l}8\\ -9\end{array}& \begin{array}{l}6\\ 10\end{array}\end{array}\right]\end{array}$

Calculation:

First multiply A by 3, and then subtract B from 3A to solve $B-3A$ as shown below.

Thus, $B-3A$ is $\left[\begin{array}{ccc}\begin{array}{l}-11\\ 8\end{array}& \begin{array}{l}-7\\ -9\end{array}& \begin{array}{l}27\\ -2\end{array}\end{array}\right]$ .