# Math Help - Basic determinants

1. ## Basic determinants

Need help with some basic determinants ( atleast I think thats basic stuff ). I know I must create Determinant from first, but im not sure how - do I need to take those free numbers behind equal sign? Second goes by determinant properties, but evrything I tryed didnt work.

2. ## Re: Basic determinants

Hey skaters.

Do you know the inductive formula for a determinant? Once you know that then calculating the determinant for any square matrix (provided it has finite rows/columns) is easy.

You should look at the formula in terms of cofactors (ie the inductive formula):

Minors and Cofactors: Expanding Along a Row

4. ## Re: Basic determinants

I tryed first by minors and cofactors and got "0", but when I put my matrix in matrix calculator I see It should be 50 :/
Ibdutt why did u dispose off "2" in second row and second column, am I allowed to do that?

5. ## Re: Basic determinants

Hi,
The attachment finds the determinant of the coefficient matrix of your system by "cofactors". Also the given determinant is reduced by elementary row operations. Both methods give an answer of 50. I think it's a good exercise for you to figure out what row operations I used. Hope this helps.