SOLUTION: I'm having difficulty figuring out determinants for matricies that exceed the normal 3x3 format. The exact matrix is as follows: 1 2 0 0 3 -1 4 5 -2 4 1 6 2 -1 -2 -3

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Question 5740: I'm having difficulty figuring out determinants for matricies that exceed the normal 3x3 format. The exact matrix is as follows:
1 2 0 0
3 -1 4 5
-2 4 1 6
2 -1 -2 -3
Our book explains that if two rows or columns of a square matrix A are identical, then the absolute value of A = 0 ... but none of these rows or columns are identical. I have tried the D=a11C11+a21C21+a31C31 and adding in the fourth a41C41, but my answer wasn't correct (understandably so).
Any piece of information is helpful. Thank you,
Abby

Answer by khwang(438) About Me  (Show Source):
You can put this solution on YOUR website!
Since the 1st row containing twozeros,
expanding it along the 1st row, we have
D = a11C11 - a12C12 = 1*(-20) + (-2)*61 = -142

Kenny