# How do you expand a cofactor?

## How do you expand a cofactor?

Expansion by cofactors involves following any row or column of a determinant and multiplying each element of the row or column by its cofactor. The sum of these products equals the value of the determinant.

## What are the cofactors of a matrix?

A cofactor is the number you get when you remove the column and row of a designated element in a matrix, which is just a numerical grid in the form of a rectangle or a square. The cofactor is always preceded by a positive (+) or negative (-) sign, depending whether the element is in a + or – position.

What is the order of matrix?

The order of matrix is general represented as Am×n A m × n , where m is the number of rows, and n is the number of columns in the given matrix. Also, the multiplication answer of the order of matrix (m × n) gives the number of elements in the matrix.

What is the difference between cofactor and minor?

1. What is the Difference Between Cofactors and Minors of a Matrix? Minor of an element of a square matrix is the determinant that we get by deleting the row and the column in which the element appears. The cofactor of an element of a square matrix is the minor of the element with a proper sign.

### Why do you multiply a different row of cofactors is 0?

Multiplying a row by the co-factors of any other row will mean that the row itself is duplicated in the determinant being evaluated. So a determinant with two identical rows will be a determinant with a row replaced by difference of those rows (a row full of zeros) and thus it will be zero.

### Under what conditions the rank of the matrix A is 3?

Matrix A has only one linearly independent row, so its rank is 1. Hence, matrix A is not full rank. Now, look at matrix B. All of its rows are linearly independent, so the rank of matrix B is 3.

Can rank of a matrix be zero?

The zero matrix is the only matrix whose rank is 0.

What is minor expansion?

Also known as “Laplacian” determinant expansion by minors, expansion by minors is a technique for computing the determinant of a given square matrix. . Although efficient for small matrices, techniques such as Gaussian elimination are much more efficient when the matrix size becomes large.

#### When do you add a co factor to a matrix?

So co-factors are the number you get when you eliminate the row and column of a designated element in a matrix, which is just a grid in the form of a square or a rectangle. The co-factor is always preceded by a negative (-) or a positive (+) sign, depending on whether the number is in a + or – position.

#### How to find a determinant using cofactor expansion?

The cofactor expansion theorem, also called Laplace expansion, states that any determinant can be computed by adding the products of the elements of a column or row by their respective cofactors.

What is the determinant of a cofactor of a matrix?

The minors are based on the columns and rows that are deleted. For instance, if you eliminate the fourth column and the second row of the matrix, the determinant of the matrix is M2,4 . So cofactors are the number you get when you eliminate the row and column of a designated element in a matrix, which is just a grid in the form…

Which is the right hand side of the cofactor expansion?

We often say the right-hand side is the cofactor expansion of the determinant along row \\(i\\). (This formula can be proved directly from the definition of the determinant.)