Question

Can someone please help to explain something to me?

Answer 1

yea

Answer 2

When doing matrices; finding the determinant of a 3x3 matrix. \[\left[\begin{matrix}1 & 2&3 \\ -1& 0&1\\ -2&3&1\end{matrix}\right]\]

When you expand on Row 1 you get

Answer 3

\[1\left[\begin{matrix}0 & 1 \\ 2 & 1\end{matrix}\right]+2(-\left[\begin{matrix}-1 & 1 \\ -2 & 1\end{matrix}\right])+(-3)\left[\begin{matrix}-1 & 0 \\ 2 & 2\end{matrix}\right]\] But why is the second "term" \[2(-\left[\begin{matrix}-1 & 1 \\ -2 & 1\end{matrix}\right])\] 2 times the negative of the matrix???

Answer 4

That is the case for the even elements if I remember correctly, also be careful that first one should have a 3 on the bottom.

Answer 5

oops, the 3 in the original matrix on the bottom should be a 2

Answer 6

Anyway, Thanks :)

Answer 7

Better come back and give this problem more time and effort. Unfortunately there are several errors in your work that need to be cleared up.