Identify the elementary row operation being performed to obtain the new row-equivalent matrix.

Question

Original Matrix. New row-equivalent Matrix

[ 4 -1 -5 ] [ 4 -1 -5 ]

[ -5 4 9 ] [11 0 -11]

Answer 1

The operation was to add 4 times the top row to the bottom row, and replace the bottom row with the result. You can easily verity this:

-5 + 4(4) = 11

4 + 4(-1) = 0

9 + 4(-5) = -11