**Perform the row operation, $-2R_1\rightarrow R_1$, on the following matrix.** $\left[\begin{array} {ccc} -7 & -9 & 4 & 6 \\ 0 & -6 & -4 & 0 \\ 2 & -6 & 2 & 1 \end{array} \right] $ [[☃ matrix 1]]