Precalculus Examples

$(x + 3) (x - 6 - 5 i) (x - 6 + 5 i)$

Step 1

Expand $(x + 3) (x - 6 - 5 i)$ by multiplying each term in the first expression by each term in the second expression.

$(x \cdot x + x \cdot - 6 + x (- 5 i) + 3 x + 3 \cdot - 6 + 3 (- 5 i)) (x - 6 + 5 i)$

Step 2

Simplify terms.

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Step 2.1

Simplify each term.

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Step 2.1.1

Multiply $x$ by $x$ .

$(x^{2} + x \cdot - 6 + x (- 5 i) + 3 x + 3 \cdot - 6 + 3 (- 5 i)) (x - 6 + 5 i)$

Step 2.1.2

Move $- 6$ to the left of $x$ .

$(x^{2} - 6 \cdot x + x (- 5 i) + 3 x + 3 \cdot - 6 + 3 (- 5 i)) (x - 6 + 5 i)$

Step 2.1.3

Multiply $3$ by $- 6$ .

$(x^{2} - 6 x + x (- 5 i) + 3 x - 18 + 3 (- 5 i)) (x - 6 + 5 i)$

Step 2.1.4

Multiply $- 5$ by $3$ .

$(x^{2} - 6 x + x (- 5 i) + 3 x - 18 - 15 i) (x - 6 + 5 i)$

Step 2.2

Add $- 6 x$ and $3 x$ .

$(x^{2} + x (- 5 i) - 3 x - 18 - 15 i) (x - 6 + 5 i)$

Step 3

Expand $(x^{2} + x (- 5 i) - 3 x - 18 - 15 i) (x - 6 + 5 i)$ by multiplying each term in the first expression by each term in the second expression.

$x^{2} x + x^{2} \cdot - 6 + x^{2} (5 i) + x (- 5 i) x + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4

Simplify terms.

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Step 4.1

Simplify each term.

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Step 4.1.1

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

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Step 4.1.1.1

Multiply $x^{2}$ by $x$ .

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Step 4.1.1.1.1

Raise $x$ to the power of $1$ .

$x^{2} x^{1} + x^{2} \cdot - 6 + x^{2} (5 i) + x (- 5 i) x + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.1.1.2

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

$x^{2 + 1} + x^{2} \cdot - 6 + x^{2} (5 i) + x (- 5 i) x + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.1.2

Add $2$ and $1$ .

$x^{3} + x^{2} \cdot - 6 + x^{2} (5 i) + x (- 5 i) x + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.2

Move $- 6$ to the left of $x^{2}$ .

$x^{3} - 6 \cdot x^{2} + x^{2} (5 i) + x (- 5 i) x + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.3

Move $5$ to the left of $x^{2}$ .

$x^{3} - 6 x^{2} + 5 \cdot x^{2} i + x (- 5 i) x + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.4

Multiply $x$ by $x$ by adding the exponents.

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Step 4.1.4.1

Move $x$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x \cdot x (- 5 i) + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.4.2

Multiply $x$ by $x$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + x (- 5 i) \cdot - 6 + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.5

Multiply $- 6$ by $- 5$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + x (30 i) + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.6

Move $30$ to the left of $x$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 \cdot x i + x (- 5 i) (5 i) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.7

Multiply $x (- 5 i) (5 i)$ .

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Step 4.1.7.1

Multiply $5$ by $- 5$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + x (- 25 i) i - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.7.2

Raise $i$ to the power of $1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + x (- 25 (i^{1} i)) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.7.3

Raise $i$ to the power of $1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + x (- 25 (i^{1} i^{1})) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.7.4

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

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + x (- 25 i^{1 + 1}) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.7.5

Add $1$ and $1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + x (- 25 i^{2}) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.8

Rewrite $i^{2}$ as $- 1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + x (- 25 \cdot - 1) - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.9

Multiply $- 25$ by $- 1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + x \cdot 25 - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.10

Move $25$ to the left of $x$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 \cdot x - 3 x \cdot x - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.11

Multiply $x$ by $x$ by adding the exponents.

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Step 4.1.11.1

Move $x$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 (x \cdot x) - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.11.2

Multiply $x$ by $x$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} - 3 x \cdot - 6 - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.12

Multiply $- 6$ by $- 3$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 3 x (5 i) - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.13

Multiply $5$ by $- 3$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x - 18 \cdot - 6 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.14

Multiply $- 18$ by $- 6$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 18 (5 i) - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.15

Multiply $5$ by $- 18$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x - 15 i \cdot - 6 - 15 i (5 i)$

Step 4.1.16

Multiply $- 6$ by $- 15$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i - 15 i (5 i)$

Step 4.1.17

Multiply $- 15 i (5 i)$ .

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Step 4.1.17.1

Multiply $5$ by $- 15$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i - 75 i i$

Step 4.1.17.2

Raise $i$ to the power of $1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i - 75 (i^{1} i)$

Step 4.1.17.3

Raise $i$ to the power of $1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i - 75 (i^{1} i^{1})$

Step 4.1.17.4

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

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i - 75 i^{1 + 1}$

Step 4.1.17.5

Add $1$ and $1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i - 75 i^{2}$

Step 4.1.18

Rewrite $i^{2}$ as $- 1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i - 75 \cdot - 1$

Step 4.1.19

Multiply $- 75$ by $- 1$ .

$x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i + 75$

Step 4.2

Simplify by adding terms.

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Step 4.2.1

Combine the opposite terms in $x^{3} - 6 x^{2} + 5 x^{2} i + x^{2} (- 5 i) + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i + 75$ .

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Step 4.2.1.1

Reorder the factors in the terms $5 x^{2} i$ and $x^{2} (- 5 i)$ .

$x^{3} - 6 x^{2} + 5 i x^{2} - 5 i x^{2} + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i + 75$

Step 4.2.1.2

Subtract $5 i x^{2}$ from $5 i x^{2}$ .

$x^{3} - 6 x^{2} + 0 + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i + 75$

Step 4.2.1.3

Add $x^{3} - 6 x^{2}$ and $0$ .

$x^{3} - 6 x^{2} + 30 x i + 25 x - 3 x^{2} + 18 x - 15 x i - 18 x + 108 - 90 i - 15 i x + 90 i + 75$

Step 4.2.1.4

Subtract $18 x$ from $18 x$ .

$x^{3} - 6 x^{2} + 30 x i + 25 x - 3 x^{2} - 15 x i + 0 + 108 - 90 i - 15 i x + 90 i + 75$

Step 4.2.1.5

Add $x^{3} - 6 x^{2} + 30 x i + 25 x - 3 x^{2} - 15 x i$ and $0$ .

$x^{3} - 6 x^{2} + 30 x i + 25 x - 3 x^{2} - 15 x i + 108 - 90 i - 15 i x + 90 i + 75$

Step 4.2.1.6

Add $- 90 i$ and $90 i$ .

$x^{3} - 6 x^{2} + 30 x i + 25 x - 3 x^{2} - 15 x i + 108 - 15 i x + 0 + 75$

Step 4.2.1.7

Add $x^{3} - 6 x^{2} + 30 x i + 25 x - 3 x^{2} - 15 x i + 108 - 15 i x$ and $0$ .

$x^{3} - 6 x^{2} + 30 x i + 25 x - 3 x^{2} - 15 x i + 108 - 15 i x + 75$

Step 4.2.2

Subtract $3 x^{2}$ from $- 6 x^{2}$ .

$x^{3} - 9 x^{2} + 30 x i + 25 x - 15 x i + 108 - 15 i x + 75$

Step 4.2.3

Subtract $15 x i$ from $30 x i$ .

$x^{3} - 9 x^{2} + 15 x i + 25 x + 108 - 15 i x + 75$

Step 4.2.4

Combine the opposite terms in $x^{3} - 9 x^{2} + 15 x i + 25 x + 108 - 15 i x + 75$ .

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Step 4.2.4.1

Reorder the factors in the terms $15 x i$ and $- 15 i x$ .

$x^{3} - 9 x^{2} + 15 i x + 25 x + 108 - 15 i x + 75$

Step 4.2.4.2

Subtract $15 i x$ from $15 i x$ .

$x^{3} - 9 x^{2} + 25 x + 108 + 0 + 75$

Step 4.2.4.3

Add $x^{3} - 9 x^{2} + 25 x + 108$ and $0$ .

$x^{3} - 9 x^{2} + 25 x + 108 + 75$

Step 4.2.5

Add $108$ and $75$ .

$x^{3} - 9 x^{2} + 25 x + 183$