3.3-8 ===== A matrix is in reduced row echelon form <==> the corresponding homogeneous system of equations is a reduced echelon system. There is a simple criterion for testing if a given matrix B is in reduced row echelon form: TEST: Each nonzero row of B has a leading one, and the leading one sits in a column of the identity. Finally, these identity columns appear in natural order as consecutive initial columns of the identity. The textbook reports the answer as the 3x3 identity matrix. Details expected include a frame sequence that starts with matrix A and ends with the identity. Document all steps with detailed information in the form swap(s,t), combo(s,t,c), mult(t,m). 3.3-18 ====== The textbook reports the correct answer as a 3x5 identity matrix B. Details expected include a frame sequence that starts with matrix A and ends with matrix B. Document all steps with detailed information in the form swap(s,t), combo(s,t,c), mult(t,m). The matrix B is a reduced row echelon form, because the nonzero rows are rows 1 and 2, and each contains a leading one, which sits in a column of the 3x3 identity matrix I. These columns are the first two columns of I in natural order.