Question

If A = `[(7,1), (2,5)]` and B = `[(1,2), (3,-1)]` then verify that |AB| = |A|  |B|.

Answer 1

A = `[(7,1), (2,5)]` and B = `[(1,2), (3,-1)]`

AB = `[(7,1), (2,5)]` `[(1,2), (3,-1)]`

= `[(10,13), (17,-1)]`

|AB| = `|(10,13), (17,-1)|` = -10 - 221 = -231

Now, |A| = `|(7,1), (2,5)|` = 35 - 2 = 33

and |B| = `|(1,2), (3,-1)|` = -1 - 6 = -7

|A| |B| = 33 x -7 = -231

|AB| = |A| |B|