One of the following operations on the rows of a matrix:
exchange two rows
\(R_i \leftrightarrow R_j\)
replace a row a by a non-zero constant multiple of itself
\(R_i \gets kR_i\) with \(k \neq 0\)
replace any row a by the sum of itself and a multiple of another row
\(R_i \gets R_i + kR_j\) with \(i \neq j\)