The matrix represents a system of equations. the 3 by 4 matrix, row 1, column 1, 2 column 2, negative 1 column 3, negative 3 column 4, negative 20 row 2, column 1, negative 2 column 2, negative 6 column 3, 6 column 4, negative 4 row 3, column 1, 0 column 2, 3 column 3, negative 2 column 4, negative 9 Which matrix represents 1 half cap r 2 plus cap r 3 rightarrow cap r 3 ?