Question

How do you find the determinant of this matrix by hand?
3, 2, 1
1, 0, -1
0, 1, 2

Answer 1

3*[..] - 2*[..]+1*[..]

Answer 2

ive seen one way that takes the first 2 columns and copies them to the right side; then does a diagonal

Answer 3

do you multiply or do add them?

Answer 4

3 2 1 3 2
1 0 -1 1 0
0 1 2 0 1
---------------------



3 2 1
0 -1 1
2 0 1
---------------------
0+0+1 = 1


1 3 2
0 -1 1
0 1 2
---------------------
0-3+4 = 1

Answer 5

the left side I believe is the negative so we get:

1/-1 = -1

Answer 6

to compare this with a more normal method ....

Answer 7

3
0 -1
1 2
--------
3(0(2)-1(-1)) = 3(1) = 3


2
1 -1
0 2
----------
-2(1(2)-0(-1) = -2(2) = -4



1
1 0
0 1
--------
1(1(0)-0(1)) = 1(0) = 0

add up the results:

3-4+0 = -1