Precalculus Examples

${(x + 6 y)}^{4}$

Step 1

Use the binomial expansion theorem to find each term. The binomial theorem states ${(a + b)}^{n} = \sum_{k = 0}^{n} n C k \cdot (a^{n - k} b^{k})$ .

$\sum_{k = 0}^{4} \frac{4!}{(4 - k)! k!} \cdot {(x)}^{4 - k} \cdot {(6 y)}^{k}$

Step 2

Expand the summation.

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

Step 3

Simplify the exponents for each term of the expansion.

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

Step 4

Simplify each term.

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Step 4.1

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

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

Step 4.2

Apply the product rule to $6 y$ .

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

Step 4.3

Rewrite using the commutative property of multiplication.

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

Step 4.4

Anything raised to $0$ is $1$ .

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

Step 4.5

Multiply $x^{4}$ by $1$ .

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

Step 4.6

Anything raised to $0$ is $1$ .

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

Step 4.7

Multiply $x^{4}$ by $1$ .

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

Step 4.8

Simplify.

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

Step 4.9

Rewrite using the commutative property of multiplication.

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

Step 4.10

Multiply $4$ by $6$ .

$x^{4} + 24 x^{3} y + 6 \cdot {(x)}^{2} \cdot {(6 y)}^{2} + 4 \cdot {(x)}^{1} \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.11

Apply the product rule to $6 y$ .

$x^{4} + 24 x^{3} y + 6 x^{2} \cdot (6^{2} y^{2}) + 4 \cdot {(x)}^{1} \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.12

Rewrite using the commutative property of multiplication.

$x^{4} + 24 x^{3} y + 6 \cdot 6^{2} x^{2} y^{2} + 4 \cdot {(x)}^{1} \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.13

Multiply $6$ by $6^{2}$ by adding the exponents.

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Step 4.13.1

Multiply $6$ by $6^{2}$ .

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Step 4.13.1.1

Raise $6$ to the power of $1$ .

$x^{4} + 24 x^{3} y + 6^{1} \cdot 6^{2} x^{2} y^{2} + 4 \cdot {(x)}^{1} \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.13.1.2

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

$x^{4} + 24 x^{3} y + 6^{1 + 2} x^{2} y^{2} + 4 \cdot {(x)}^{1} \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.13.2

Add $1$ and $2$ .

$x^{4} + 24 x^{3} y + 6^{3} x^{2} y^{2} + 4 \cdot {(x)}^{1} \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.14

Raise $6$ to the power of $3$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 4 \cdot {(x)}^{1} \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.15

Simplify.

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 4 \cdot x \cdot {(6 y)}^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.16

Apply the product rule to $6 y$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 4 x \cdot (6^{3} y^{3}) + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.17

Rewrite using the commutative property of multiplication.

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 4 \cdot 6^{3} x y^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.18

Raise $6$ to the power of $3$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 4 \cdot 216 x y^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.19

Multiply $4$ by $216$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 864 x y^{3} + 1 \cdot {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.20

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

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 864 x y^{3} + {(x)}^{0} \cdot {(6 y)}^{4}$

Step 4.21

Anything raised to $0$ is $1$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 864 x y^{3} + 1 \cdot {(6 y)}^{4}$

Step 4.22

Multiply ${(6 y)}^{4}$ by $1$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 864 x y^{3} + {(6 y)}^{4}$

Step 4.23

Apply the product rule to $6 y$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 864 x y^{3} + 6^{4} y^{4}$

Step 4.24

Raise $6$ to the power of $4$ .

$x^{4} + 24 x^{3} y + 216 x^{2} y^{2} + 864 x y^{3} + 1296 y^{4}$