Find the ranks of the following matrices.

$\text{rank} \left[\begin{array}{cc} 2 &-7\cr 2 &-7 \end{array}\right] =$

$\text{rank} \left[\begin{array}{ccc} -1 &3 &-2\cr 1 &7 &0\cr -9 &0 &0 \end{array}\right] =$

$\text{rank} \left[\begin{array}{cc} 1 &2\cr 7 &-3 \end{array}\right] =$