Linear Algebra Examples

⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦

$[\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}]$

Step 1

Set up the formula to find the characteristic equation

p (λ)

$p (λ)$ .

p (λ) = determinant (A - λ I_{3})

$p (λ) = determinant (A - λ I_{3})$

Step 2

The identity matrix or unit matrix of size

3

$3$ is the

3 \times 3

$3 \times 3$ square matrix with ones on the main diagonal and zeros elsewhere.

⎡ ⎢ ⎣ \begin{matrix} 1 & 0 & 0 0 & 1 & 0 0 & 0 & 1 \end{matrix} ⎤ ⎥ ⎦

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

Step 3

Substitute the known values into

p (λ) = determinant (A - λ I_{3})

$p (λ) = determinant (A - λ I_{3})$ .

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Step 3.1

Substitute

⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦

$[\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}]$ for

A

$A$ .

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ - λ I_{3} ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] - λ I_{3})$

Step 3.2

Substitute

⎡ ⎢ ⎣ \begin{matrix} 1 & 0 & 0 0 & 1 & 0 0 & 0 & 1 \end{matrix} ⎤ ⎥ ⎦

$[\begin{array}{c} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array}]$ for

I_{3}

$I_{3}$ .

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ - λ ⎡ ⎢ ⎣ \begin{matrix} 1 & 0 & 0 0 & 1 & 0 0 & 0 & 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] - λ [\begin{array}{c} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array}])$

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ - λ ⎡ ⎢ ⎣ \begin{matrix} 1 & 0 & 0 0 & 1 & 0 0 & 0 & 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] - λ [\begin{array}{c} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array}])$

Step 4

Simplify.

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Step 4.1

Simplify each term.

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Step 4.1.1

Multiply

- λ

$- λ$ by each element of the matrix.

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ + ⎡ ⎢ ⎣ \begin{matrix} - λ \cdot 1 & - λ \cdot 0 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ \cdot 1 & - λ \cdot 0 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2

Simplify each element in the matrix.

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Step 4.1.2.1

Multiply

- 1

$- 1$ by

1

$1$ .

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ + ⎡ ⎢ ⎣ \begin{matrix} - λ & - λ \cdot 0 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & - λ \cdot 0 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.2

Multiply

- λ \cdot 0

$- λ \cdot 0$ .

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Step 4.1.2.2.1

Multiply

0

$0$ by

- 1

$- 1$ .

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ + ⎡ ⎢ ⎣ \begin{matrix} - λ & 0 λ & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 λ & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.2.2

Multiply

0

$0$ by

λ

$λ$ .

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ + ⎡ ⎢ ⎣ \begin{matrix} - λ & 0 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ + ⎡ ⎢ ⎣ \begin{matrix} - λ & 0 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

Step 4.1.2.3

Multiply

- λ \cdot 0

$- λ \cdot 0$ .

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Step 4.1.2.3.1

Multiply

0

$0$ by

- 1

$- 1$ .

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ + ⎡ ⎢ ⎣ \begin{matrix} - λ & 0 & 0 λ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 λ \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.3.2

Multiply

0

$0$ by

λ

$λ$ .

p (λ) = determinant ⎛ ⎜ ⎝ ⎡ ⎢ ⎣ \begin{matrix} - 2 & 6 & - 7 3 & - 9 & 10 - 1 & 3 & - 3 \end{matrix} ⎤ ⎥ ⎦ + ⎡ ⎢ ⎣ \begin{matrix} - λ & 0 & 0 - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{matrix} ⎤ ⎥ ⎦ ⎞ ⎟ ⎠

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.4

Multiply

$- λ \cdot 0$ .

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Step 4.1.2.4.1

Multiply

$0$ by

$- 1$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 λ & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.4.2

Multiply

$0$ by

$λ$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.5

Multiply

$- 1$ by

$1$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.6

Multiply

$- λ \cdot 0$ .

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Step 4.1.2.6.1

Multiply

$0$ by

$- 1$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 λ \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.6.2

Multiply

$0$ by

$λ$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.7

Multiply

$- λ \cdot 0$ .

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Step 4.1.2.7.1

Multiply

$0$ by

$- 1$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 λ & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.7.2

Multiply

$0$ by

$λ$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.8

Multiply

$- λ \cdot 0$ .

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Step 4.1.2.8.1

Multiply

$0$ by

$- 1$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & 0 λ & - λ \cdot 1 \end{array}])$

Step 4.1.2.8.2

Multiply

$0$ by

$λ$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.9

Multiply

$- 1$ by

$1$ .

$p (λ) = determinant ([\begin{array}{c} - 2 & 6 & - 7 \\ 3 & - 9 & 10 \\ - 1 & 3 & - 3 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & 0 & - λ \end{array}])$

Step 4.2

Add the corresponding elements.

$p (λ) = determinant [\begin{array}{c} - 2 - λ & 6 + 0 & - 7 + 0 \\ 3 + 0 & - 9 - λ & 10 + 0 \\ - 1 + 0 & 3 + 0 & - 3 - λ \end{array}]$

Step 4.3

Simplify each element.

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Step 4.3.1

Add

$6$ and

$0$ .

$p (λ) = determinant [\begin{array}{c} - 2 - λ & 6 & - 7 + 0 \\ 3 + 0 & - 9 - λ & 10 + 0 \\ - 1 + 0 & 3 + 0 & - 3 - λ \end{array}]$

Step 4.3.2

Add

$- 7$ and

$0$ .

$p (λ) = determinant [\begin{array}{c} - 2 - λ & 6 & - 7 \\ 3 + 0 & - 9 - λ & 10 + 0 \\ - 1 + 0 & 3 + 0 & - 3 - λ \end{array}]$

Step 4.3.3

Add

$3$ and

$0$ .

$p (λ) = determinant [\begin{array}{c} - 2 - λ & 6 & - 7 \\ 3 & - 9 - λ & 10 + 0 \\ - 1 + 0 & 3 + 0 & - 3 - λ \end{array}]$

Step 4.3.4

Add

$10$ and

$0$ .

$p (λ) = determinant [\begin{array}{c} - 2 - λ & 6 & - 7 \\ 3 & - 9 - λ & 10 \\ - 1 + 0 & 3 + 0 & - 3 - λ \end{array}]$

Step 4.3.5

Add

$- 1$ and

$0$ .

$p (λ) = determinant [\begin{array}{c} - 2 - λ & 6 & - 7 \\ 3 & - 9 - λ & 10 \\ - 1 & 3 + 0 & - 3 - λ \end{array}]$

Step 4.3.6

Add

$3$ and

$0$ .

$p (λ) = determinant [\begin{array}{c} - 2 - λ & 6 & - 7 \\ 3 & - 9 - λ & 10 \\ - 1 & 3 & - 3 - λ \end{array}]$

Step 5

Find the determinant.

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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.

$| \begin{array}{c} - 9 - λ & 10 \\ 3 & - 3 - λ \end{array} |$

Step 5.1.4

Multiply element

$a_{11}$ by its cofactor.

$(- 2 - λ) | \begin{array}{c} - 9 - λ & 10 \\ 3 & - 3 - λ \end{array} |$

Step 5.1.5

The minor for

$a_{12}$ is the determinant with row

$1$ and column

$2$ deleted.

$| \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} |$

Step 5.1.6

Multiply element

$a_{12}$ by its cofactor.

$- 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} |$

Step 5.1.7

The minor for

$a_{13}$ is the determinant with row

$1$ and column

$3$ deleted.

$| \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.1.8

Multiply element

$a_{13}$ by its cofactor.

$- 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.1.9

Add the terms together.

$p (λ) = (- 2 - λ) | \begin{array}{c} - 9 - λ & 10 \\ 3 & - 3 - λ \end{array} | - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2

Evaluate

$| \begin{array}{c} - 9 - λ & 10 \\ 3 & - 3 - λ \end{array} |$ .

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Step 5.2.1

The determinant of a

$2 \times 2$ matrix can be found using the formula

$| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$p (λ) = (- 2 - λ) ((- 9 - λ) (- 3 - λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

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

Expand

$(- 9 - λ) (- 3 - λ)$ using the FOIL Method.

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Step 5.2.2.1.1.1

Apply the distributive property.

$p (λ) = (- 2 - λ) (- 9 (- 3 - λ) - λ (- 3 - λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.1.2

Apply the distributive property.

$p (λ) = (- 2 - λ) (- 9 \cdot - 3 - 9 (- λ) - λ (- 3 - λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.1.3

Apply the distributive property.

$p (λ) = (- 2 - λ) (- 9 \cdot - 3 - 9 (- λ) - λ \cdot - 3 - λ (- λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2

Simplify and combine like terms.

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Step 5.2.2.1.2.1

Simplify each term.

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Step 5.2.2.1.2.1.1

Multiply

$- 9$ by

$- 3$ .

$p (λ) = (- 2 - λ) (27 - 9 (- λ) - λ \cdot - 3 - λ (- λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.1.2

Multiply

$- 1$ by

$- 9$ .

$p (λ) = (- 2 - λ) (27 + 9 λ - λ \cdot - 3 - λ (- λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.1.3

Multiply

$- 3$ by

$- 1$ .

$p (λ) = (- 2 - λ) (27 + 9 λ + 3 λ - λ (- λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.1.4

Rewrite using the commutative property of multiplication.

$p (λ) = (- 2 - λ) (27 + 9 λ + 3 λ - 1 \cdot - 1 λ \cdot λ - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.1.5

Multiply

$λ$ by

$λ$ by adding the exponents.

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Step 5.2.2.1.2.1.5.1

Move

$λ$ .

$p (λ) = (- 2 - λ) (27 + 9 λ + 3 λ - 1 \cdot - 1 (λ \cdot λ) - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.1.5.2

Multiply

$λ$ by

$λ$ .

$p (λ) = (- 2 - λ) (27 + 9 λ + 3 λ - 1 \cdot - 1 λ^{2} - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.1.6

Multiply

$- 1$ by

$- 1$ .

$p (λ) = (- 2 - λ) (27 + 9 λ + 3 λ + 1 λ^{2} - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.1.7

Multiply

$λ^{2}$ by

$1$ .

$p (λ) = (- 2 - λ) (27 + 9 λ + 3 λ + λ^{2} - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.2.2

Add

$9 λ$ and

$3 λ$ .

$p (λ) = (- 2 - λ) (27 + 12 λ + λ^{2} - 3 \cdot 10) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.1.3

Multiply

$- 3$ by

$10$ .

$p (λ) = (- 2 - λ) (27 + 12 λ + λ^{2} - 30) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.2

Subtract

$30$ from

$27$ .

$p (λ) = (- 2 - λ) (12 λ + λ^{2} - 3) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.2.2.3

Reorder

$12 λ$ and

$λ^{2}$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 | \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} | - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.3

Evaluate

$| \begin{array}{c} 3 & 10 \\ - 1 & - 3 - λ \end{array} |$ .

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Step 5.3.1

The determinant of a

$2 \times 2$ matrix can be found using the formula

$| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (3 (- 3 - λ) - (- 1 \cdot 10)) - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

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

Apply the distributive property.

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (3 \cdot - 3 + 3 (- λ) - (- 1 \cdot 10)) - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.3.2.1.2

Multiply

$3$ by

$- 3$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 9 + 3 (- λ) - (- 1 \cdot 10)) - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.3.2.1.3

Multiply

$- 1$ by

$3$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 9 - 3 λ - (- 1 \cdot 10)) - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.3.2.1.4

Multiply

$- (- 1 \cdot 10)$ .

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Step 5.3.2.1.4.1

Multiply

$- 1$ by

$10$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 9 - 3 λ - - 10) - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.3.2.1.4.2

Multiply

$- 1$ by

$- 10$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 9 - 3 λ + 10) - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.3.2.2

Add

$- 9$ and

$10$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 | \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$

Step 5.4

Evaluate

$| \begin{array}{c} 3 & - 9 - λ \\ - 1 & 3 \end{array} |$ .

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Step 5.4.1

The determinant of a

$2 \times 2$ matrix can be found using the formula

$| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (3 \cdot 3 - - (- 9 - λ))$

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

$3$ by

$3$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (9 - - (- 9 - λ))$

Step 5.4.2.1.2

Apply the distributive property.

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (9 - (- - 9 - - λ))$

Step 5.4.2.1.3

Multiply

$- 1$ by

$- 9$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (9 - (9 - - λ))$

Step 5.4.2.1.4

Multiply

$- - λ$ .

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Step 5.4.2.1.4.1

Multiply

$- 1$ by

$- 1$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (9 - (9 + 1 λ))$

Step 5.4.2.1.4.2

Multiply

$λ$ by

$1$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (9 - (9 + λ))$

Step 5.4.2.1.5

Apply the distributive property.

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (9 - 1 \cdot 9 - λ)$

Step 5.4.2.1.6

Multiply

$- 1$ by

$9$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (9 - 9 - λ)$

Step 5.4.2.2

Subtract

$9$ from

$9$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (0 - λ)$

Step 5.4.2.3

Subtract

$λ$ from

$0$ .

$p (λ) = (- 2 - λ) (λ^{2} + 12 λ - 3) - 6 (- 3 λ + 1) - 7 (- λ)$

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

Expand

$(- 2 - λ) (λ^{2} + 12 λ - 3)$ by multiplying each term in the first expression by each term in the second expression.

$p (λ) = - 2 λ^{2} - 2 (12 λ) - 2 \cdot - 3 - λ \cdot λ^{2} - λ (12 λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2

Simplify each term.

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Step 5.5.1.2.1

Multiply

$12$ by

$- 2$ .

$p (λ) = - 2 λ^{2} - 24 λ - 2 \cdot - 3 - λ \cdot λ^{2} - λ (12 λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.2

Multiply

$- 2$ by

$- 3$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ \cdot λ^{2} - λ (12 λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.3

Multiply

$λ$ by

$λ^{2}$ by adding the exponents.

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Step 5.5.1.2.3.1

Move

$λ^{2}$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - (λ^{2} λ) - λ (12 λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.3.2

Multiply

$λ^{2}$ by

$λ$ .

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Step 5.5.1.2.3.2.1

Raise

$λ$ to the power of

$1$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - (λ^{2} λ^{1}) - λ (12 λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.3.2.2

Use the power rule

$a^{m} a^{n} = a^{m + n}$ to combine exponents.

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ^{2 + 1} - λ (12 λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.3.3

Add

$2$ and

$1$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ^{3} - λ (12 λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.4

Rewrite using the commutative property of multiplication.

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ^{3} - 1 \cdot 12 λ \cdot λ - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.5

Multiply

$λ$ by

$λ$ by adding the exponents.

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Step 5.5.1.2.5.1

Move

$λ$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ^{3} - 1 \cdot 12 (λ \cdot λ) - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.5.2

Multiply

$λ$ by

$λ$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ^{3} - 1 \cdot 12 λ^{2} - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.6

Multiply

$- 1$ by

$12$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ^{3} - 12 λ^{2} - λ \cdot - 3 - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.2.7

Multiply

$- 3$ by

$- 1$ .

$p (λ) = - 2 λ^{2} - 24 λ + 6 - λ^{3} - 12 λ^{2} + 3 λ - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.3

Subtract

$12 λ^{2}$ from

$- 2 λ^{2}$ .

$p (λ) = - 14 λ^{2} - 24 λ + 6 - λ^{3} + 3 λ - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.4

Add

$- 24 λ$ and

$3 λ$ .

$p (λ) = - 14 λ^{2} - 21 λ + 6 - λ^{3} - 6 (- 3 λ + 1) - 7 (- λ)$

Step 5.5.1.5

Apply the distributive property.

$p (λ) = - 14 λ^{2} - 21 λ + 6 - λ^{3} - 6 (- 3 λ) - 6 \cdot 1 - 7 (- λ)$

Step 5.5.1.6

Multiply

$- 3$ by

$- 6$ .

$p (λ) = - 14 λ^{2} - 21 λ + 6 - λ^{3} + 18 λ - 6 \cdot 1 - 7 (- λ)$

Step 5.5.1.7

Multiply

$- 6$ by

$1$ .

$p (λ) = - 14 λ^{2} - 21 λ + 6 - λ^{3} + 18 λ - 6 - 7 (- λ)$

Step 5.5.1.8

Multiply

$- 1$ by

$- 7$ .

$p (λ) = - 14 λ^{2} - 21 λ + 6 - λ^{3} + 18 λ - 6 + 7 λ$

Step 5.5.2

Combine the opposite terms in

$- 14 λ^{2} - 21 λ + 6 - λ^{3} + 18 λ - 6 + 7 λ$ .

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Step 5.5.2.1

Subtract

$6$ from

$6$ .

$p (λ) = - 14 λ^{2} - 21 λ - λ^{3} + 18 λ + 0 + 7 λ$

Step 5.5.2.2

Add

$- 14 λ^{2} - 21 λ - λ^{3} + 18 λ$ and

$0$ .

$p (λ) = - 14 λ^{2} - 21 λ - λ^{3} + 18 λ + 7 λ$

Step 5.5.3

Add

$- 21 λ$ and

$18 λ$ .

$p (λ) = - 14 λ^{2} - λ^{3} - 3 λ + 7 λ$

Step 5.5.4

Add

$- 3 λ$ and

$7 λ$ .

$p (λ) = - 14 λ^{2} - λ^{3} + 4 λ$

Step 5.5.5

Reorder

$- 14 λ^{2}$ and

$- λ^{3}$ .

$p (λ) = - λ^{3} - 14 λ^{2} + 4 λ$