# How do you find the determinant by cofactor expansion?

## How do you find the determinant by cofactor expansion?

One way of computing the determinant of an n×n matrix A is to use the following formula called the cofactor formula. Pick any i∈{1,…,n}. Then det(A)=(−1)i+1Ai,1det(A(i∣1))+(−1)i+2Ai,2det(A(i∣2))+⋯+(−1)i+nAi,ndet(A(i∣n)).

## What is the determinant of a 4×4 matrix?

Determinant of a 4×4 matrix is a unique number that is also calculated using a particular formula. If a matrix order is in n x n, then it is a square matrix. So, here 4×4 is a square matrix that has four rows and four columns. If A is a square matrix then the determinant of the matrix A is represented as |A|.

## How do you find determinant without cofactor expansion?

In order to find the determinant, we have to add the first and second rows. Now, we may factor (x + y + z) from the first row. After factor (x + y + z) first row and third row will be identical. Hence the answer is 0.

## When would you use cofactor expansion?

Cofactor expansions are most useful when computing the determinant of a matrix that has a row or column with several zero entries. Indeed, if the ( i , j ) entry of A is zero, then there is no reason to compute the ( i , j ) cofactor.

## Can a determinant of a matrix be 0?

When the determinant of a matrix is zero, the volume of the region with sides given by its columns or rows is zero, which means the matrix considered as a transformation takes the basis vectors into vectors that are linearly dependent and define 0 volume.

## How do you identify determinants?

Here are the steps to go through to find the determinant.

1. Pick any row or column in the matrix. It does not matter which row or which column you use, the answer will be the same for any row.
2. Multiply every element in that row or column by its cofactor and add. The result is the determinant.

## How do you expand a determinant?

Expanding to Find the Determinant

1. Pick any row or column in the matrix. It does not matter which row or which column you use, the answer will be the same for any row.
2. Multiply every element in that row or column by its cofactor and add. The result is the determinant.