Question

If you switch the first row with the fourth row, what will the new first row be?
$\left[\begin{array}{cccc}3& 4& 2& 11\\ 9& 1& 0& 0\\ 0& 1& 0& 2\\ 0& 0& 6& 1\end{array}\right]$

• A. $3,4,2,11$
• B. $9,1,0,0$
• C. $0,1,0,2$
• D. $0,0,6,1$
• E. $0,2,0,3$

Answer 1

The correct option is D $0,0,6,1$

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

First and fourth row are interchanged

New matrix obtained $=\left[\begin{array}{cccc}0& 0& 6& 1\\ 9& 1& 0& 0\\ 0& 1& 0& 2\\ 3& 4& 2& 1\end{array}\right]$

New first row$=\left[\begin{array}{cccc}0& 0& 6& 1\end{array}\right]$ Option D