# Thread: Determine the determinant of a 4x4 matrix using cramer's rule?

1. ## Determine the determinant of a 4x4 matrix using cramer's rule?

1/2 0 2/3 1
2 -2 1/2 0
0 4 1/4 1
-2 0 3/4 -1

and

-2 1/2 1 8
4 8 -1 0
0 -2 4 6
1 -3 2 0

How do I go about doing these? Sorry if there aren't any brackets I don't know how to put them there. If you guys still can't make it out, there's an attachment of the equation.

Thank you!

2. Originally Posted by strigy
1/2 0 2/3 1
2 -2 1/2 0
0 4 1/4 1
-2 0 3/4 -1

and

-2 1/2 1 8
4 8 -1 0
0 -2 4 6
1 -3 2 0

How do I go about doing these? Sorry if there aren't any brackets I don't know how to put them there. If you guys still can't make it out, there's an attachment of the equation.

Thank you!
Cramer's rule is not for the evaluation of determinants but for the solution of sets of n linear equations in n unknowns. Do you mean evaluate the determinants by cofactor expansion?

CB

3. I guess using the cofactor method in a 5x5 matrices is quite long. Try to transform first you rmatrix to echelon form (Gauss' algorithm) then evalute the determinants.

4. Originally Posted by FailCalculus
I guess using the cofactor method in a 5x5 matrices is quite long. Try to transform first you rmatrix to echelon form (Gauss' algorithm) then evalute the determinants.
They are 4x4

CB