What is the row echelon form of (1111)\begin{pmatrix} 1 & 1 \\ 1 & 1 \end{pmatrix}(1111)?
(1100)\begin{pmatrix} 1 & 1 \\ 0 & 0 \end{pmatrix}(1010)
(0011)\begin{pmatrix} 0 & 0 \\ 1 & 1 \end{pmatrix}(0101)
(1001)\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}(1001)
(1111)\begin{pmatrix} 1 & 1 \\ 1 & 1 \end{pmatrix}(1111)