Thread: Matrix co-factors

In an exercise in my linear algebra book, I'm supposed to find all the co-factors for the matrix:

1 -2 3
6 7 -1
-3 1 4

I've got all of them right, except C31, and C32.

The answers I got, were:

C31 = 23, C32 = -17

According to the book, the correct answer is:

C31 = -19, C32 = 19

Am I wrong or is there an error in the book?

Thanks!

No, you're wrong. Check the definition again and tell us what you have done: Cofactor.

Thanks, for some reason I started adding the terms instead of subtracting when figuring out the minor entries!