Examples

$[\begin{array}{c} 1 & 1 & 2 & 3 \\ 0 & 2 & 1 & 4 \\ 2 & 1 & 2 & 3 \\ 2 & 1 & 1 & 0 \end{array}]$

Step 1

Choose the row or column with the most $0$ elements. If there are no $0$ elements choose any row or column. Multiply every element in column $1$ by its cofactor and add.

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Step 1.1

Consider the corresponding sign chart.

$| \begin{array}{c} + & - & + & - \\ - & + & - & + \\ + & - & + & - \\ - & + & - & + \end{array} |$

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 $a_{11}$ is the determinant with row $1$ and column $1$ deleted.

$| \begin{array}{c} 2 & 1 & 4 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} |$

Step 1.4

Multiply element $a_{11}$ by its cofactor.

$1 | \begin{array}{c} 2 & 1 & 4 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} |$

Step 1.5

The minor for $a_{21}$ is the determinant with row $2$ and column $1$ deleted.

$| \begin{array}{c} 1 & 2 & 3 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} |$

Step 1.6

Multiply element $a_{21}$ by its cofactor.

$0 | \begin{array}{c} 1 & 2 & 3 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} |$

Step 1.7

The minor for $a_{31}$ is the determinant with row $3$ and column $1$ deleted.

$| \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} |$

Step 1.8

Multiply element $a_{31}$ by its cofactor.

$2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} |$

Step 1.9

The minor for $a_{41}$ is the determinant with row $4$ and column $1$ deleted.

$| \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 1.10

Multiply element $a_{41}$ by its cofactor.

$- 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 1.11

Add the terms together.

$1 | \begin{array}{c} 2 & 1 & 4 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} | + 0 | \begin{array}{c} 1 & 2 & 3 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} | + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 2

Multiply $0$ by $| \begin{array}{c} 1 & 2 & 3 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} |$ .

$1 | \begin{array}{c} 2 & 1 & 4 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} | + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3

Evaluate $| \begin{array}{c} 2 & 1 & 4 \\ 1 & 2 & 3 \\ 1 & 1 & 0 \end{array} |$ .

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Step 3.1

Choose the row or column with the most $0$ elements. If there are no $0$ elements choose any row or column. Multiply every element in row $3$ by its cofactor and add.

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Step 3.1.1

Consider the corresponding sign chart.

$| \begin{array}{c} + & - & + \\ - & + & - \\ + & - & + \end{array} |$

Step 3.1.2

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

Step 3.1.3

The minor for $a_{31}$ is the determinant with row $3$ and column $1$ deleted.

$| \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} |$

Step 3.1.4

Multiply element $a_{31}$ by its cofactor.

$1 | \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} |$

Step 3.1.5

The minor for $a_{32}$ is the determinant with row $3$ and column $2$ deleted.

$| \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} |$

Step 3.1.6

Multiply element $a_{32}$ by its cofactor.

$- 1 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} |$

Step 3.1.7

The minor for $a_{33}$ is the determinant with row $3$ and column $3$ deleted.

$| \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |$

Step 3.1.8

Multiply element $a_{33}$ by its cofactor.

$0 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |$

Step 3.1.9

Add the terms together.

$1 (1 | \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} | - 1 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 0 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.2

Multiply $0$ by $| \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |$ .

$1 (1 | \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} | - 1 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.3

Evaluate $| \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} |$ .

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Step 3.3.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$1 (1 (1 \cdot 3 - 2 \cdot 4) - 1 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.3.2

Simplify the determinant.

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Step 3.3.2.1

Simplify each term.

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Step 3.3.2.1.1

Multiply $3$ by $1$ .

$1 (1 (3 - 2 \cdot 4) - 1 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.3.2.1.2

Multiply $- 2$ by $4$ .

$1 (1 (3 - 8) - 1 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.3.2.2

Subtract $8$ from $3$ .

$1 (1 \cdot - 5 - 1 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.4

Evaluate $| \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} |$ .

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Step 3.4.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$1 (1 \cdot - 5 - 1 (2 \cdot 3 - 1 \cdot 4) + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.4.2

Simplify the determinant.

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Step 3.4.2.1

Simplify each term.

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Step 3.4.2.1.1

Multiply $2$ by $3$ .

$1 (1 \cdot - 5 - 1 (6 - 1 \cdot 4) + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.4.2.1.2

Multiply $- 1$ by $4$ .

$1 (1 \cdot - 5 - 1 (6 - 4) + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.4.2.2

Subtract $4$ from $6$ .

$1 (1 \cdot - 5 - 1 \cdot 2 + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.5

Simplify the determinant.

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Step 3.5.1

Simplify each term.

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Step 3.5.1.1

Multiply $- 5$ by $1$ .

$1 (- 5 - 1 \cdot 2 + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.5.1.2

Multiply $- 1$ by $2$ .

$1 (- 5 - 2 + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.5.2

Subtract $2$ from $- 5$ .

$1 (- 7 + 0) + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 3.5.3

Add $- 7$ and $0$ .

$1 \cdot - 7 + 0 + 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} | - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4

Evaluate $| \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 1 & 0 \end{array} |$ .

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Step 4.1

Choose the row or column with the most $0$ elements. If there are no $0$ elements choose any row or column. Multiply every element in row $3$ by its cofactor and add.

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Step 4.1.1

Consider the corresponding sign chart.

$| \begin{array}{c} + & - & + \\ - & + & - \\ + & - & + \end{array} |$

Step 4.1.2

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

Step 4.1.3

The minor for $a_{31}$ is the determinant with row $3$ and column $1$ deleted.

$| \begin{array}{c} 2 & 3 \\ 1 & 4 \end{array} |$

Step 4.1.4

Multiply element $a_{31}$ by its cofactor.

$1 | \begin{array}{c} 2 & 3 \\ 1 & 4 \end{array} |$

Step 4.1.5

The minor for $a_{32}$ is the determinant with row $3$ and column $2$ deleted.

$| \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} |$

Step 4.1.6

Multiply element $a_{32}$ by its cofactor.

$- 1 | \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} |$

Step 4.1.7

The minor for $a_{33}$ is the determinant with row $3$ and column $3$ deleted.

$| \begin{array}{c} 1 & 2 \\ 2 & 1 \end{array} |$

Step 4.1.8

Multiply element $a_{33}$ by its cofactor.

$0 | \begin{array}{c} 1 & 2 \\ 2 & 1 \end{array} |$

Step 4.1.9

Add the terms together.

$1 \cdot - 7 + 0 + 2 (1 | \begin{array}{c} 2 & 3 \\ 1 & 4 \end{array} | - 1 | \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} | + 0 | \begin{array}{c} 1 & 2 \\ 2 & 1 \end{array} |) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.2

Multiply $0$ by $| \begin{array}{c} 1 & 2 \\ 2 & 1 \end{array} |$ .

$1 \cdot - 7 + 0 + 2 (1 | \begin{array}{c} 2 & 3 \\ 1 & 4 \end{array} | - 1 | \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} | + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.3

Evaluate $| \begin{array}{c} 2 & 3 \\ 1 & 4 \end{array} |$ .

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Step 4.3.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$1 \cdot - 7 + 0 + 2 (1 (2 \cdot 4 - 1 \cdot 3) - 1 | \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} | + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.3.2

Simplify the determinant.

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Step 4.3.2.1

Simplify each term.

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Step 4.3.2.1.1

Multiply $2$ by $4$ .

$1 \cdot - 7 + 0 + 2 (1 (8 - 1 \cdot 3) - 1 | \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} | + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.3.2.1.2

Multiply $- 1$ by $3$ .

$1 \cdot - 7 + 0 + 2 (1 (8 - 3) - 1 | \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} | + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.3.2.2

Subtract $3$ from $8$ .

$1 \cdot - 7 + 0 + 2 (1 \cdot 5 - 1 | \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} | + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.4

Evaluate $| \begin{array}{c} 1 & 3 \\ 2 & 4 \end{array} |$ .

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Step 4.4.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$1 \cdot - 7 + 0 + 2 (1 \cdot 5 - 1 (1 \cdot 4 - 2 \cdot 3) + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.4.2

Simplify the determinant.

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Step 4.4.2.1

Simplify each term.

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Step 4.4.2.1.1

Multiply $4$ by $1$ .

$1 \cdot - 7 + 0 + 2 (1 \cdot 5 - 1 (4 - 2 \cdot 3) + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.4.2.1.2

Multiply $- 2$ by $3$ .

$1 \cdot - 7 + 0 + 2 (1 \cdot 5 - 1 (4 - 6) + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.4.2.2

Subtract $6$ from $4$ .

$1 \cdot - 7 + 0 + 2 (1 \cdot 5 - 1 \cdot - 2 + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.5

Simplify the determinant.

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Step 4.5.1

Simplify each term.

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Step 4.5.1.1

Multiply $5$ by $1$ .

$1 \cdot - 7 + 0 + 2 (5 - 1 \cdot - 2 + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.5.1.2

Multiply $- 1$ by $- 2$ .

$1 \cdot - 7 + 0 + 2 (5 + 2 + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.5.2

Add $5$ and $2$ .

$1 \cdot - 7 + 0 + 2 (7 + 0) - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 4.5.3

Add $7$ and $0$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 | \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$

Step 5

Evaluate $| \begin{array}{c} 1 & 2 & 3 \\ 2 & 1 & 4 \\ 1 & 2 & 3 \end{array} |$ .

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Step 5.1

Choose the row or column with the most $0$ elements. If there are no $0$ elements choose any row or column. Multiply every element in row $1$ by its cofactor and add.

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Step 5.1.1

Consider the corresponding sign chart.

$| \begin{array}{c} + & - & + \\ - & + & - \\ + & - & + \end{array} |$

Step 5.1.2

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

Step 5.1.3

The minor for $a_{11}$ is the determinant with row $1$ and column $1$ deleted.

$| \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} |$

Step 5.1.4

Multiply element $a_{11}$ by its cofactor.

$1 | \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} |$

Step 5.1.5

The minor for $a_{12}$ is the determinant with row $1$ and column $2$ deleted.

$| \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} |$

Step 5.1.6

Multiply element $a_{12}$ by its cofactor.

$- 2 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} |$

Step 5.1.7

The minor for $a_{13}$ is the determinant with row $1$ and column $3$ deleted.

$| \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |$

Step 5.1.8

Multiply element $a_{13}$ by its cofactor.

$3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |$

Step 5.1.9

Add the terms together.

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 | \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} | - 2 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.2

Evaluate $| \begin{array}{c} 1 & 4 \\ 2 & 3 \end{array} |$ .

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Step 5.2.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 (1 \cdot 3 - 2 \cdot 4) - 2 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.2.2

Simplify the determinant.

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Step 5.2.2.1

Simplify each term.

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Step 5.2.2.1.1

Multiply $3$ by $1$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 (3 - 2 \cdot 4) - 2 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.2.2.1.2

Multiply $- 2$ by $4$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 (3 - 8) - 2 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.2.2.2

Subtract $8$ from $3$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 | \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} | + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.3

Evaluate $| \begin{array}{c} 2 & 4 \\ 1 & 3 \end{array} |$ .

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Step 5.3.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 (2 \cdot 3 - 1 \cdot 4) + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.3.2

Simplify the determinant.

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Step 5.3.2.1

Simplify each term.

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Step 5.3.2.1.1

Multiply $2$ by $3$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 (6 - 1 \cdot 4) + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.3.2.1.2

Multiply $- 1$ by $4$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 (6 - 4) + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.3.2.2

Subtract $4$ from $6$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 \cdot 2 + 3 | \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |)$

Step 5.4

Evaluate $| \begin{array}{c} 2 & 1 \\ 1 & 2 \end{array} |$ .

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Step 5.4.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 \cdot 2 + 3 (2 \cdot 2 - 1 \cdot 1))$

Step 5.4.2

Simplify the determinant.

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Step 5.4.2.1

Simplify each term.

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Step 5.4.2.1.1

Multiply $2$ by $2$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 \cdot 2 + 3 (4 - 1 \cdot 1))$

Step 5.4.2.1.2

Multiply $- 1$ by $1$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 \cdot 2 + 3 (4 - 1))$

Step 5.4.2.2

Subtract $1$ from $4$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (1 \cdot - 5 - 2 \cdot 2 + 3 \cdot 3)$

Step 5.5

Simplify the determinant.

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Step 5.5.1

Simplify each term.

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Step 5.5.1.1

Multiply $- 5$ by $1$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (- 5 - 2 \cdot 2 + 3 \cdot 3)$

Step 5.5.1.2

Multiply $- 2$ by $2$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (- 5 - 4 + 3 \cdot 3)$

Step 5.5.1.3

Multiply $3$ by $3$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (- 5 - 4 + 9)$

Step 5.5.2

Subtract $4$ from $- 5$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 (- 9 + 9)$

Step 5.5.3

Add $- 9$ and $9$ .

$1 \cdot - 7 + 0 + 2 \cdot 7 - 2 \cdot 0$

Step 6

Simplify the determinant.

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Step 6.1

Simplify each term.

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Step 6.1.1

Multiply $- 7$ by $1$ .

$- 7 + 0 + 2 \cdot 7 - 2 \cdot 0$

Step 6.1.2

Multiply $2$ by $7$ .

$- 7 + 0 + 14 - 2 \cdot 0$

Step 6.1.3

Multiply $- 2$ by $0$ .

$- 7 + 0 + 14 + 0$

Step 6.2

Add $- 7$ and $0$ .

$- 7 + 14 + 0$

Step 6.3

Add $- 7$ and $14$ .

$7 + 0$

Step 6.4

Add $7$ and $0$ .

$7$

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