Question

What is the result when you add the matrix $\left[\begin{array}{cc}4& 5\end{array}\right]$ to the matrix $\left[\begin{array}{cc}7& -3\end{array}\right]$ and multiply the result by $2$?

• A. $\left[\begin{array}{cc}2& 6\end{array}\right]$
• B. $\left[\begin{array}{cc}11& 2\end{array}\right]$
• C. $\left[\begin{array}{cc}22& 4\end{array}\right]$
• D. $\left[\begin{array}{cc}28& -15\end{array}\right]$
• E. $\left[\begin{array}{cc}54& -30\end{array}\right]$

Answer 1

Answer: (C)

$\left[\begin{array}{cc}22& 4\end{array}\right]$

Given are the matrix
$\left[\begin{array}{cc}4& 5\end{array}\right]$ and $\left[\begin{array}{cc}7& -3\end{array}\right]$
On adding both, we get
$\left[\begin{array}{cc}4& 5\end{array}\right]$ $+$ $\left[\begin{array}{cc}7& -3\end{array}\right]$
$=\left[\begin{array}{cc}11& 2\end{array}\right]$
On multiplying by $2$, we get
$\left[\begin{array}{cc}11& 2\end{array}\right]\times 2$ $=\left[\begin{array}{cc}22& 4\end{array}\right]$