Question 3 What is the rank r of the matrix \begin{array}{l}

\left(\begin{array}{ccc}

4 & -5 & -1 \\

-5 & 5 & 0 \\

2 & -4 & -2 \\

0 & 0 & -1 \\

0 & -3 & -2

\end{array}\right) ? \\

r=

\end{array}