Question

Which of the following is the new row that results when you add rows $1$ and $3$?
$\left[\begin{array}{cccc}3& 4& 2& 11\\ 9& 1& 0& 0\\ 0& 1& 0& 2\\ 0& 0& 6& 1\end{array}\right]$

• A. $6,8,4,22$
• B. $3,5,2,13$
• C. $3,4,2,11$
• D. $3,4,8,12$
• E. $4,5,3,12$

Answer 1

The correct option is B $3,5,2,13$

Given Matrix$=\left[\begin{array}{cccc}3& 4& 2& 11\\ 9& 1& 0& 0\\ 0& 1& 0& 2\\ 0& 0& 6& 1\end{array}\right]$

Row $1=\left[\begin{array}{cccc}3& 4& 2& 11\end{array}\right]$

Row $3=\left[\begin{array}{cccc}0& 1& 0& 2\end{array}\right]$

Sum$=\left[\begin{array}{cccc}3+0& 4+1& 2+0& 11+2\end{array}\right]$

$\left[\begin{array}{cccc}3& 5& 2& 13\end{array}\right]$

$\therefore$Option $2$ is correct