Question

The rank of the matrix $A=\left[\begin{array}{ccc}-1& 2& 3\\ -2& 4& 6\end{array}\right]$ is

• A. $3$
• B. $2$
• C. $1$
• D. $0$

Answer 1

The correct option is A $3$

$A=\left[\begin{array}{ccc}-1& 2& 3\\ -2& 4& 6\end{array}\right]$

$R_2\to R_2-2R_1$

$A=\left[\begin{array}{ccc}-1& 2& 3\\ 0& 0& 0\end{array}\right]$

Rank of matrix $A=1$