# Precalculus Examples

Step 1

Step 1.1

Consider the corresponding sign chart.

Step 1.2

The cofactor is the minor with the sign changed if the indices match a position on the sign chart.

Step 1.3

The minor for is the determinant with row and column deleted.

Step 1.4

Multiply element by its cofactor.

Step 1.5

The minor for is the determinant with row and column deleted.

Step 1.6

Multiply element by its cofactor.

Step 1.7

The minor for is the determinant with row and column deleted.

Step 1.8

Multiply element by its cofactor.

Step 1.9

Add the terms together.

Step 2

Multiply by .

Step 3

Step 3.1

The determinant of a matrix can be found using the formula .

Step 3.2

Simplify the determinant.

Step 3.2.1

Simplify each term.

Step 3.2.1.1

Multiply by .

Step 3.2.1.2

Multiply by .

Step 3.2.2

Subtract from .

Step 4

Step 4.1

The determinant of a matrix can be found using the formula .

Step 4.2

Simplify the determinant.

Step 4.2.1

Simplify each term.

Step 4.2.1.1

Multiply by .

Step 4.2.1.2

Multiply by .

Step 4.2.2

Subtract from .

Step 5

Step 5.1

Simplify each term.

Step 5.1.1

Multiply by .

Step 5.1.2

Multiply by .

Step 5.2

Add and .

Step 5.3

Add and .