# How do I find the determinant of a 3xx3 matrix?

Sep 7, 2015

Use co-factor expansion along any row or column of your choice.
If a row or column contains a zero entry, then it is time-efficient to use that row or column

#### Explanation:

Recall that by co-factor expansion we mean adding all the entries in a particular row or column 1 at a time, multiplied by the co-factor multiplied by the minor of the entry ${\left(- 1\right)}^{i + j} {M}_{i j}$
The minor is the 2x2 determinant that remains when you delete row I and column j, and it is found in normal methods.

Let me show an example - attached :