The matrix $A$ below has $\lambda=2$ as an eigenvalue. Find the geometric multiplicity of $\lambda=2$ using your calculator only for row-reducing matrices. \begin{equation*} A= \begin{bmatrix} 18 & -15 & 33 & -15\\ -4 & 8 & -6 & 6\\ -9 & 9 & -16 & 9\\ 5 & -6 & 9 & -4 \end{bmatrix} \end{equation*}