The determinant of a 3 × 3 matrix A is defined as follows.
The determinant of a 3 × 3 matrix can also be found using the method of “diagonals.”
Step 1 Rewrite columns 1 and 2 of matrix A to the right of matrix A.
Step 2 Identify the diagonals d1 through d6 and multiply their elements.
Step 3 Find the sum of the products from d1, d2, and d3.
Step 4 Subtract the sum of the products from d4, d5, and d6 from that sum:
(d1 + d) + d3) – (d4 + d5 + d6).
Verify that this method produces the same results as the previous method given.