Precalculus Examples

${(2 x + 1)}^{4}$

Step 1

Pascal's Triangle can be displayed as such:

$1$

$1 - 1$

$1 - 2 - 1$

$1 - 3 - 3 - 1$

$1 - 4 - 6 - 4 - 1$

The triangle can be used to calculate the coefficients of the expansion of ${(a + b)}^{n}$ by taking the exponent $n$ and adding $1$ . The coefficients will correspond with line $n + 1$ of the triangle. For ${(2 x + 1)}^{4}$ , $n = 4$ so the coefficients of the expansion will correspond with line $5$ .

Step 2

The expansion follows the rule ${(a + b)}^{n} = c_{0} a^{n} b^{0} + c_{1} a^{n - 1} b^{1} + c_{n - 1} a^{1} b^{n - 1} + c_{n} a^{0} b^{n}$ . The values of the coefficients, from the triangle, are $1 - 4 - 6 - 4 - 1$ .

$1 a^{4} b^{0} + 4 a^{3} b + 6 a^{2} b^{2} + 4 a b^{3} + 1 a^{0} b^{4}$

Step 3

Substitute the actual values of $a$ $2 x$ and $b$ $1$ into the expression.

$1 {(2 x)}^{4} {(1)}^{0} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4

Simplify each term.

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Step 4.1

Multiply $1$ by ${(1)}^{0}$ by adding the exponents.

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Step 4.1.1

Move ${(1)}^{0}$ .

${(1)}^{0} \cdot 1 {(2 x)}^{4} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.1.2

Multiply ${(1)}^{0}$ by $1$ .

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Step 4.1.2.1

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

${(1)}^{0} \cdot 1^{1} {(2 x)}^{4} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.1.2.2

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

$1^{0 + 1} {(2 x)}^{4} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.1.3

Add $0$ and $1$ .

$1^{1} {(2 x)}^{4} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.2

Simplify $1^{1} {(2 x)}^{4}$ .

${(2 x)}^{4} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.3

Apply the product rule to $2 x$ .

$2^{4} x^{4} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.4

Raise $2$ to the power of $4$ .

$16 x^{4} + 4 {(2 x)}^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.5

Apply the product rule to $2 x$ .

$16 x^{4} + 4 (2^{3} x^{3}) {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.6

Raise $2$ to the power of $3$ .

$16 x^{4} + 4 (8 x^{3}) {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.7

Multiply $8$ by $4$ .

$16 x^{4} + 32 x^{3} {(1)}^{1} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.8

Evaluate the exponent.

$16 x^{4} + 32 x^{3} \cdot 1 + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.9

Multiply $32$ by $1$ .

$16 x^{4} + 32 x^{3} + 6 {(2 x)}^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.10

Apply the product rule to $2 x$ .

$16 x^{4} + 32 x^{3} + 6 (2^{2} x^{2}) {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.11

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

$16 x^{4} + 32 x^{3} + 6 (4 x^{2}) {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.12

Multiply $4$ by $6$ .

$16 x^{4} + 32 x^{3} + 24 x^{2} {(1)}^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.13

One to any power is one.

$16 x^{4} + 32 x^{3} + 24 x^{2} \cdot 1 + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.14

Multiply $24$ by $1$ .

$16 x^{4} + 32 x^{3} + 24 x^{2} + 4 {(2 x)}^{1} {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.15

Simplify.

$16 x^{4} + 32 x^{3} + 24 x^{2} + 4 (2 x) {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.16

Multiply $2$ by $4$ .

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x {(1)}^{3} + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.17

One to any power is one.

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x \cdot 1 + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.18

Multiply $8$ by $1$ .

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x + 1 {(2 x)}^{0} {(1)}^{4}$

Step 4.19

Multiply $1$ by ${(1)}^{4}$ by adding the exponents.

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Step 4.19.1

Move ${(1)}^{4}$ .

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x + {(1)}^{4} \cdot 1 {(2 x)}^{0}$

Step 4.19.2

Multiply ${(1)}^{4}$ by $1$ .

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Step 4.19.2.1

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

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x + {(1)}^{4} \cdot 1^{1} {(2 x)}^{0}$

Step 4.19.2.2

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

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x + 1^{4 + 1} {(2 x)}^{0}$

Step 4.19.3

Add $4$ and $1$ .

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x + 1^{5} {(2 x)}^{0}$

Step 4.20

Simplify $1^{5} {(2 x)}^{0}$ .

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x + 1^{5}$

Step 4.21

One to any power is one.

$16 x^{4} + 32 x^{3} + 24 x^{2} + 8 x + 1$