Elementary Row Matricies
alexwang0518
How do you figure out what 'elementary matrix' to multiply by when computing the determinant? Weisbart did an example where he found the determinant by E1E2E3E4...=I (where En is an elementary row matrix) but he didn't explain how he got the elementary row matrices, he kind of just wrote them. Help appreciated!
brookewenig: May 29, 2015, 8:29 p.m.
Are you referring to the lecture from week 7, Monday? If so, the 'elementary matrices' were determined by the operation you performed on each row. For instance, to go from the matrix A= 1 3 2 2 1 0 1 0 1 to A'= 1 3 2 0 -5 -4 0 -3 -1 You subtracted Row1 from Row2 twice, and subtracted Row1 from Row3 once. Thus, this yields E1: 1 0 0 -2 1 0 -1 0 1 You can check your work by multiplying E1 with the original A to get A'. Does that make sense?