Algebra Examples

${(3 x + y)}^{4}$

Step 1

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

$\sum_{k = 0}^{4} \frac{4!}{(4 - k)! k!} \cdot {(3 x)}^{4 - k} \cdot {(y)}^{k}$

Step 2

Expand the summation.

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

Step 3

Simplify the exponents for each term of the expansion.

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

Step 4

Simplify each term.

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Step 4.1

Multiply ${(3 x)}^{4}$ by $1$ .

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

Step 4.2

Apply the product rule to $3 x$ .

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

Step 4.3

Raise $3$ to the power of $4$ .

$81 x^{4} \cdot {(y)}^{0} + 4 \cdot {(3 x)}^{3} \cdot {(y)}^{1} + 6 \cdot {(3 x)}^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.4

Anything raised to $0$ is $1$ .

$81 x^{4} \cdot 1 + 4 \cdot {(3 x)}^{3} \cdot {(y)}^{1} + 6 \cdot {(3 x)}^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.5

Multiply $81$ by $1$ .

$81 x^{4} + 4 \cdot {(3 x)}^{3} \cdot {(y)}^{1} + 6 \cdot {(3 x)}^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.6

Apply the product rule to $3 x$ .

$81 x^{4} + 4 \cdot (3^{3} x^{3}) \cdot {(y)}^{1} + 6 \cdot {(3 x)}^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.7

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

$81 x^{4} + 4 \cdot (27 x^{3}) \cdot {(y)}^{1} + 6 \cdot {(3 x)}^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.8

Multiply $27$ by $4$ .

$81 x^{4} + 108 x^{3} \cdot {(y)}^{1} + 6 \cdot {(3 x)}^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.9

Simplify.

$81 x^{4} + 108 x^{3} \cdot y + 6 \cdot {(3 x)}^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.10

Apply the product rule to $3 x$ .

$81 x^{4} + 108 x^{3} y + 6 \cdot (3^{2} x^{2}) \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.11

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

$81 x^{4} + 108 x^{3} y + 6 \cdot (9 x^{2}) \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.12

Multiply $9$ by $6$ .

$81 x^{4} + 108 x^{3} y + 54 x^{2} \cdot {(y)}^{2} + 4 \cdot {(3 x)}^{1} \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.13

Simplify.

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 4 \cdot (3 x) \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.14

Multiply $3$ by $4$ .

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 12 x \cdot {(y)}^{3} + 1 \cdot {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.15

Multiply ${(3 x)}^{0}$ by $1$ .

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 12 x y^{3} + {(3 x)}^{0} \cdot {(y)}^{4}$

Step 4.16

Apply the product rule to $3 x$ .

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 12 x y^{3} + 3^{0} x^{0} \cdot {(y)}^{4}$

Step 4.17

Anything raised to $0$ is $1$ .

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 12 x y^{3} + 1 x^{0} \cdot {(y)}^{4}$

Step 4.18

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

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 12 x y^{3} + x^{0} \cdot {(y)}^{4}$

Step 4.19

Anything raised to $0$ is $1$ .

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 12 x y^{3} + 1 \cdot {(y)}^{4}$

Step 4.20

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

$81 x^{4} + 108 x^{3} y + 54 x^{2} y^{2} + 12 x y^{3} + y^{4}$