- #1

rocomath

- 1,755

- 1

If a multiple of one row is added to another row, the value of the determinant is not changed. This applies to columns, also.

15 14 16

18 17 32

21 20 42

Factoring a 3 from C1 and a 2 from C3 =

6 times

5 14 13

6 17 13

7 20 21

Now subtracting C3 from C2 =

6 times

5 1 13

6 1 16

7 -1 21

So, C3-C2. Why isn't C2 ...

13-14 = -1

16-17 = -1

21-20 = 1

I notice it's just opposite signs, but where does the -1 multiple come from.