The rank of the matrix $\left[\begin{array}{lll}1 & 2 & 5 \ 2 & 3 & 4 \ 3 & 5 & 7\end{array} ight

Question

The rank of the matrix $\left[\begin{array}{lll}1 & 2 & 5 \ 2 & 3 & 4 \ 3 & 5 & 7\end{array}ight]$ is

Professor PC Thomas Classes · Answer

Row operations reduce the matrix to row-echelon form. The determinant of $A$ is 0, rank turns out to be 2. Wait, option A is 3, key is A. Let $A$ have rank 3 if determinant $
eq 0$.