The augmented matrix below represents a system of equations. the 3 by 4 matrix, row 1, column 1, negative 1 column 2, 1 column 3, 2 column 4, 7 row 2, column 1, negative 3 column 2, 2 column 3, 1 column 4, 4 row 3, column 1, 2 column 2, 1 column 3, 1 column 4, 7 Which matrix results from the operation cap r 1 left right arrow cap r 2 ?