Question

Multiplication of $\left[\begin{array}{ccc}4& 1& 1\\ 2& 3& 1\end{array}\right]$ with $5$ gives

• A. $\left[\begin{array}{ccc}20& 1& 1\\ 2& 3& 1\end{array}\right]$
• B. $\left[\begin{array}{ccc}20& 5& 5\\ 10& 15& 5\end{array}\right]$
• C. $\left[\begin{array}{ccc}4& 1& 1\\ 10& 15& 5\end{array}\right]$
• D. None of the above

Answer 1

Answer: (B)

$\left[\begin{array}{ccc}20& 5& 5\\ 10& 15& 5\end{array}\right]$

Given matrix $\left[\begin{array}{ccc}4& 1& 1\\ 2& 3& 1\end{array}\right]$

Now,

$=5\times \left[\begin{array}{ccc}4& 1& 1\\ 2& 3& 1\end{array}\right]$

$=\left[\begin{array}{ccc}5\times 4& 5\times 1& 5\times 1\\ 5\times 2& 5\times 3& 5\times 1\end{array}\right]$

$=\left[\begin{array}{ccc}20& 5& 5\\ 10& 15& 5\end{array}\right]$

Option B is correct