Linear Algebra Examples

$[\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}]$

Step 1

Set up the formula to find the characteristic equation $p (λ)$ .

$p (λ) = determinant (A - λ I_{3})$

Step 2

The identity matrix or unit matrix of size $3$ is the $3 \times 3$ square matrix with ones on the main diagonal and zeros elsewhere.

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

Step 3

Substitute the known values into $p (λ) = determinant (A - λ I_{3})$ .

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Step 3.1

Substitute $[\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}]$ for $A$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] - λ I_{3})$

Step 3.2

Substitute $[\begin{array}{c} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array}]$ for $I_{3}$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] - λ [\begin{array}{c} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array}])$

Step 4

Simplify.

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Step 4.1

Simplify each term.

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Step 4.1.1

Multiply $- λ$ by each element of the matrix.

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ \cdot 1 & - λ \cdot 0 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2

Simplify each element in the matrix.

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Step 4.1.2.1

Multiply $- 1$ by $1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & - λ \cdot 0 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.2

Multiply $- λ \cdot 0$ .

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Step 4.1.2.2.1

Multiply $0$ by $- 1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 λ & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.2.2

Multiply $0$ by $λ$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.3

Multiply $- λ \cdot 0$ .

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Step 4.1.2.3.1

Multiply $0$ by $- 1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 λ \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.3.2

Multiply $0$ by $λ$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ - λ \cdot 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.4

Multiply $- λ \cdot 0$ .

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Step 4.1.2.4.1

Multiply $0$ by $- 1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 λ & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.4.2

Multiply $0$ by $λ$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ \cdot 1 & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.5

Multiply $- 1$ by $1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & - λ \cdot 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.6

Multiply $- λ \cdot 0$ .

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Step 4.1.2.6.1

Multiply $0$ by $- 1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 λ \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.6.2

Multiply $0$ by $λ$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ - λ \cdot 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.7

Multiply $- λ \cdot 0$ .

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Step 4.1.2.7.1

Multiply $0$ by $- 1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 λ & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.7.2

Multiply $0$ by $λ$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & - λ \cdot 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.8

Multiply $- λ \cdot 0$ .

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Step 4.1.2.8.1

Multiply $0$ by $- 1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & 0 λ & - λ \cdot 1 \end{array}])$

Step 4.1.2.8.2

Multiply $0$ by $λ$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & 0 & - λ \cdot 1 \end{array}])$

Step 4.1.2.9

Multiply $- 1$ by $1$ .

$p (λ) = determinant ([\begin{array}{c} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array}] + [\begin{array}{c} - λ & 0 & 0 \\ 0 & - λ & 0 \\ 0 & 0 & - λ \end{array}])$

Step 4.2

Add the corresponding elements.

$p (λ) = determinant [\begin{array}{c} 1 - λ & 2 + 0 & 3 + 0 \\ 4 + 0 & 5 - λ & 6 + 0 \\ 7 + 0 & 8 + 0 & 9 - λ \end{array}]$

Step 4.3

Simplify each element.

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Step 4.3.1

Add $2$ and $0$ .

$p (λ) = determinant [\begin{array}{c} 1 - λ & 2 & 3 + 0 \\ 4 + 0 & 5 - λ & 6 + 0 \\ 7 + 0 & 8 + 0 & 9 - λ \end{array}]$

Step 4.3.2

Add $3$ and $0$ .

$p (λ) = determinant [\begin{array}{c} 1 - λ & 2 & 3 \\ 4 + 0 & 5 - λ & 6 + 0 \\ 7 + 0 & 8 + 0 & 9 - λ \end{array}]$

Step 4.3.3

Add $4$ and $0$ .

$p (λ) = determinant [\begin{array}{c} 1 - λ & 2 & 3 \\ 4 & 5 - λ & 6 + 0 \\ 7 + 0 & 8 + 0 & 9 - λ \end{array}]$

Step 4.3.4

Add $6$ and $0$ .

$p (λ) = determinant [\begin{array}{c} 1 - λ & 2 & 3 \\ 4 & 5 - λ & 6 \\ 7 + 0 & 8 + 0 & 9 - λ \end{array}]$

Step 4.3.5

Add $7$ and $0$ .

$p (λ) = determinant [\begin{array}{c} 1 - λ & 2 & 3 \\ 4 & 5 - λ & 6 \\ 7 & 8 + 0 & 9 - λ \end{array}]$

Step 4.3.6

Add $8$ and $0$ .

$p (λ) = determinant [\begin{array}{c} 1 - λ & 2 & 3 \\ 4 & 5 - λ & 6 \\ 7 & 8 & 9 - λ \end{array}]$

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.

$| \begin{array}{c} 5 - λ & 6 \\ 8 & 9 - λ \end{array} |$

Step 5.1.4

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

$(1 - λ) | \begin{array}{c} 5 - λ & 6 \\ 8 & 9 - λ \end{array} |$

Step 5.1.5

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

$| \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} |$

Step 5.1.6

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

$- 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} |$

Step 5.1.7

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

$| \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.1.8

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

$3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.1.9

Add the terms together.

$p (λ) = (1 - λ) | \begin{array}{c} 5 - λ & 6 \\ 8 & 9 - λ \end{array} | - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2

Evaluate $| \begin{array}{c} 5 - λ & 6 \\ 8 & 9 - λ \end{array} |$ .

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Step 5.2.1

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

$p (λ) = (1 - λ) ((5 - λ) (9 - λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

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 $(5 - λ) (9 - λ)$ using the FOIL Method.

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Step 5.2.2.1.1.1

Apply the distributive property.

$p (λ) = (1 - λ) (5 (9 - λ) - λ (9 - λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.1.2

Apply the distributive property.

$p (λ) = (1 - λ) (5 \cdot 9 + 5 (- λ) - λ (9 - λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.1.3

Apply the distributive property.

$p (λ) = (1 - λ) (5 \cdot 9 + 5 (- λ) - λ \cdot 9 - λ (- λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

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 $5$ by $9$ .

$p (λ) = (1 - λ) (45 + 5 (- λ) - λ \cdot 9 - λ (- λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.2.1.2

Multiply $- 1$ by $5$ .

$p (λ) = (1 - λ) (45 - 5 λ - λ \cdot 9 - λ (- λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.2.1.3

Multiply $9$ by $- 1$ .

$p (λ) = (1 - λ) (45 - 5 λ - 9 λ - λ (- λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.2.1.4

Rewrite using the commutative property of multiplication.

$p (λ) = (1 - λ) (45 - 5 λ - 9 λ - 1 \cdot - 1 λ \cdot λ - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

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 $λ$ .

$p (λ) = (1 - λ) (45 - 5 λ - 9 λ - 1 \cdot - 1 (λ \cdot λ) - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.2.1.5.2

Multiply $λ$ by $λ$ .

$p (λ) = (1 - λ) (45 - 5 λ - 9 λ - 1 \cdot - 1 λ^{2} - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.2.1.6

Multiply $- 1$ by $- 1$ .

$p (λ) = (1 - λ) (45 - 5 λ - 9 λ + 1 λ^{2} - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.2.1.7

Multiply $λ^{2}$ by $1$ .

$p (λ) = (1 - λ) (45 - 5 λ - 9 λ + λ^{2} - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.2.2

Subtract $9 λ$ from $- 5 λ$ .

$p (λ) = (1 - λ) (45 - 14 λ + λ^{2} - 8 \cdot 6) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.1.3

Multiply $- 8$ by $6$ .

$p (λ) = (1 - λ) (45 - 14 λ + λ^{2} - 48) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.2

Subtract $48$ from $45$ .

$p (λ) = (1 - λ) (- 14 λ + λ^{2} - 3) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.2.2.3

Reorder $- 14 λ$ and $λ^{2}$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 | \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} | + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.3

Evaluate $| \begin{array}{c} 4 & 6 \\ 7 & 9 - λ \end{array} |$ .

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Step 5.3.1

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

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (4 (9 - λ) - 7 \cdot 6) + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

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.

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (4 \cdot 9 + 4 (- λ) - 7 \cdot 6) + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.3.2.1.2

Multiply $4$ by $9$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (36 + 4 (- λ) - 7 \cdot 6) + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.3.2.1.3

Multiply $- 1$ by $4$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (36 - 4 λ - 7 \cdot 6) + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.3.2.1.4

Multiply $- 7$ by $6$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (36 - 4 λ - 42) + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.3.2.2

Subtract $42$ from $36$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 | \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$

Step 5.4

Evaluate $| \begin{array}{c} 4 & 5 - λ \\ 7 & 8 \end{array} |$ .

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Step 5.4.1

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

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 (4 \cdot 8 - 7 (5 - λ))$

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 $4$ by $8$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 (32 - 7 (5 - λ))$

Step 5.4.2.1.2

Apply the distributive property.

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 (32 - 7 \cdot 5 - 7 (- λ))$

Step 5.4.2.1.3

Multiply $- 7$ by $5$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 (32 - 35 - 7 (- λ))$

Step 5.4.2.1.4

Multiply $- 1$ by $- 7$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 (32 - 35 + 7 λ)$

Step 5.4.2.2

Subtract $35$ from $32$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 (- 3 + 7 λ)$

Step 5.4.2.3

Reorder $- 3$ and $7 λ$ .

$p (λ) = (1 - λ) (λ^{2} - 14 λ - 3) - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

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

Expand $(1 - λ) (λ^{2} - 14 λ - 3)$ by multiplying each term in the first expression by each term in the second expression.

$p (λ) = 1 λ^{2} + 1 (- 14 λ) + 1 \cdot - 3 - λ \cdot λ^{2} - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2

Simplify each term.

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Step 5.5.1.2.1

Multiply $λ^{2}$ by $1$ .

$p (λ) = λ^{2} + 1 (- 14 λ) + 1 \cdot - 3 - λ \cdot λ^{2} - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.2

Multiply $- 14 λ$ by $1$ .

$p (λ) = λ^{2} - 14 λ + 1 \cdot - 3 - λ \cdot λ^{2} - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.3

Multiply $- 3$ by $1$ .

$p (λ) = λ^{2} - 14 λ - 3 - λ \cdot λ^{2} - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.4

Multiply $λ$ by $λ^{2}$ by adding the exponents.

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Step 5.5.1.2.4.1

Move $λ^{2}$ .

$p (λ) = λ^{2} - 14 λ - 3 - (λ^{2} λ) - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.4.2

Multiply $λ^{2}$ by $λ$ .

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Step 5.5.1.2.4.2.1

Raise $λ$ to the power of $1$ .

$p (λ) = λ^{2} - 14 λ - 3 - (λ^{2} λ^{1}) - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.4.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$p (λ) = λ^{2} - 14 λ - 3 - λ^{2 + 1} - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.4.3

Add $2$ and $1$ .

$p (λ) = λ^{2} - 14 λ - 3 - λ^{3} - λ (- 14 λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.5

Rewrite using the commutative property of multiplication.

$p (λ) = λ^{2} - 14 λ - 3 - λ^{3} - 1 \cdot - 14 λ \cdot λ - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.6

Multiply $λ$ by $λ$ by adding the exponents.

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Step 5.5.1.2.6.1

Move $λ$ .

$p (λ) = λ^{2} - 14 λ - 3 - λ^{3} - 1 \cdot - 14 (λ \cdot λ) - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.6.2

Multiply $λ$ by $λ$ .

$p (λ) = λ^{2} - 14 λ - 3 - λ^{3} - 1 \cdot - 14 λ^{2} - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.7

Multiply $- 1$ by $- 14$ .

$p (λ) = λ^{2} - 14 λ - 3 - λ^{3} + 14 λ^{2} - λ \cdot - 3 - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.2.8

Multiply $- 3$ by $- 1$ .

$p (λ) = λ^{2} - 14 λ - 3 - λ^{3} + 14 λ^{2} + 3 λ - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.3

Add $λ^{2}$ and $14 λ^{2}$ .

$p (λ) = 15 λ^{2} - 14 λ - 3 - λ^{3} + 3 λ - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.4

Add $- 14 λ$ and $3 λ$ .

$p (λ) = 15 λ^{2} - 11 λ - 3 - λ^{3} - 2 (- 4 λ - 6) + 3 (7 λ - 3)$

Step 5.5.1.5

Apply the distributive property.

$p (λ) = 15 λ^{2} - 11 λ - 3 - λ^{3} - 2 (- 4 λ) - 2 \cdot - 6 + 3 (7 λ - 3)$

Step 5.5.1.6

Multiply $- 4$ by $- 2$ .

$p (λ) = 15 λ^{2} - 11 λ - 3 - λ^{3} + 8 λ - 2 \cdot - 6 + 3 (7 λ - 3)$

Step 5.5.1.7

Multiply $- 2$ by $- 6$ .

$p (λ) = 15 λ^{2} - 11 λ - 3 - λ^{3} + 8 λ + 12 + 3 (7 λ - 3)$

Step 5.5.1.8

Apply the distributive property.

$p (λ) = 15 λ^{2} - 11 λ - 3 - λ^{3} + 8 λ + 12 + 3 (7 λ) + 3 \cdot - 3$

Step 5.5.1.9

Multiply $7$ by $3$ .

$p (λ) = 15 λ^{2} - 11 λ - 3 - λ^{3} + 8 λ + 12 + 21 λ + 3 \cdot - 3$

Step 5.5.1.10

Multiply $3$ by $- 3$ .

$p (λ) = 15 λ^{2} - 11 λ - 3 - λ^{3} + 8 λ + 12 + 21 λ - 9$

Step 5.5.2

Add $- 11 λ$ and $8 λ$ .

$p (λ) = 15 λ^{2} - 3 λ - 3 - λ^{3} + 12 + 21 λ - 9$

Step 5.5.3

Add $- 3 λ$ and $21 λ$ .

$p (λ) = 15 λ^{2} + 18 λ - 3 - λ^{3} + 12 - 9$

Step 5.5.4

Add $- 3$ and $12$ .

$p (λ) = 15 λ^{2} + 18 λ - λ^{3} + 9 - 9$

Step 5.5.5

Combine the opposite terms in $15 λ^{2} + 18 λ - λ^{3} + 9 - 9$ .

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Step 5.5.5.1

Subtract $9$ from $9$ .

$p (λ) = 15 λ^{2} + 18 λ - λ^{3} + 0$

Step 5.5.5.2

Add $15 λ^{2} + 18 λ - λ^{3}$ and $0$ .

$p (λ) = 15 λ^{2} + 18 λ - λ^{3}$

Step 5.5.6

Move $18 λ$ .

$p (λ) = 15 λ^{2} - λ^{3} + 18 λ$

Step 5.5.7

Reorder $15 λ^{2}$ and $- λ^{3}$ .

$p (λ) = - λ^{3} + 15 λ^{2} + 18 λ$

Step 6

Set the characteristic polynomial equal to $0$ to find the eigenvalues $λ$ .

$- λ^{3} + 15 λ^{2} + 18 λ = 0$

Step 7

Solve for $λ$ .

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Step 7.1

Factor $- λ$ out of $- λ^{3} + 15 λ^{2} + 18 λ$ .

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Step 7.1.1

Factor $- λ$ out of $- λ^{3}$ .

$- λ \cdot λ^{2} + 15 λ^{2} + 18 λ = 0$

Step 7.1.2

Factor $- λ$ out of $15 λ^{2}$ .

$- λ \cdot λ^{2} - λ (- 15 λ) + 18 λ = 0$

Step 7.1.3

Factor $- λ$ out of $18 λ$ .

$- λ \cdot λ^{2} - λ (- 15 λ) - λ \cdot - 18 = 0$

Step 7.1.4

Factor $- λ$ out of $- λ (λ^{2}) - λ (- 15 λ)$ .

$- λ (λ^{2} - 15 λ) - λ \cdot - 18 = 0$

Step 7.1.5

Factor $- λ$ out of $- λ (λ^{2} - 15 λ) - λ (- 18)$ .

$- λ (λ^{2} - 15 λ - 18) = 0$

Step 7.2

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$λ = 0$

$λ^{2} - 15 λ - 18 = 0$

Step 7.3

Set $λ$ equal to $0$ .

$λ = 0$

Step 7.4

Set $λ^{2} - 15 λ - 18$ equal to $0$ and solve for $λ$ .

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Step 7.4.1

Set $λ^{2} - 15 λ - 18$ equal to $0$ .

$λ^{2} - 15 λ - 18 = 0$

Step 7.4.2

Solve $λ^{2} - 15 λ - 18 = 0$ for $λ$ .

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Step 7.4.2.1

Use the quadratic formula to find the solutions.

$\frac{- b \pm \sqrt{b^{2} - 4 (a c)}}{2 a}$

Step 7.4.2.2

Substitute the values $a = 1$ , $b = - 15$ , and $c = - 18$ into the quadratic formula and solve for $λ$ .

$\frac{15 \pm \sqrt{{(- 15)}^{2} - 4 \cdot (1 \cdot - 18)}}{2 \cdot 1}$

Step 7.4.2.3

Simplify.

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Step 7.4.2.3.1

Simplify the numerator.

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Step 7.4.2.3.1.1

Raise $- 15$ to the power of $2$ .

$λ = \frac{15 \pm \sqrt{225 - 4 \cdot 1 \cdot - 18}}{2 \cdot 1}$

Step 7.4.2.3.1.2

Multiply $- 4 \cdot 1 \cdot - 18$ .

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Step 7.4.2.3.1.2.1

Multiply $- 4$ by $1$ .

$λ = \frac{15 \pm \sqrt{225 - 4 \cdot - 18}}{2 \cdot 1}$

Step 7.4.2.3.1.2.2

Multiply $- 4$ by $- 18$ .

$λ = \frac{15 \pm \sqrt{225 + 72}}{2 \cdot 1}$

Step 7.4.2.3.1.3

Add $225$ and $72$ .

$λ = \frac{15 \pm \sqrt{297}}{2 \cdot 1}$

Step 7.4.2.3.1.4

Rewrite $297$ as $3^{2} \cdot 33$ .

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Step 7.4.2.3.1.4.1

Factor $9$ out of $297$ .

$λ = \frac{15 \pm \sqrt{9 (33)}}{2 \cdot 1}$

Step 7.4.2.3.1.4.2

Rewrite $9$ as $3^{2}$ .

$λ = \frac{15 \pm \sqrt{3^{2} \cdot 33}}{2 \cdot 1}$

Step 7.4.2.3.1.5

Pull terms out from under the radical.

$λ = \frac{15 \pm 3 \sqrt{33}}{2 \cdot 1}$

Step 7.4.2.3.2

Multiply $2$ by $1$ .

$λ = \frac{15 \pm 3 \sqrt{33}}{2}$

Step 7.4.2.4

The final answer is the combination of both solutions.

$λ = \frac{15 + 3 \sqrt{33}}{2}, \frac{15 - 3 \sqrt{33}}{2}$

Step 7.5

The final solution is all the values that make $- λ (λ^{2} - 15 λ - 18) = 0$ true.

$λ = 0, \frac{15 + 3 \sqrt{33}}{2}, \frac{15 - 3 \sqrt{33}}{2}$

Step 8

The result can be shown in multiple forms.

Exact Form:

$λ = 0, \frac{15 + 3 \sqrt{33}}{2}, \frac{15 - 3 \sqrt{33}}{2}$

Decimal Form:

$λ = 0, 16.11684396 \dots, - 1.11684396 \dots$