Algebra Examples

{(a + b)}^{4}

${(a + b)}^{4}$

Step 1

Use the binomial expansion theorem to find each term. The binomial theorem states

{(a + b)}^{n} = n \sum k = 0 n C k \cdot (a^{n - k} b^{k})

${(a + b)}^{n} = \sum_{k = 0}^{n} n C k \cdot (a^{n - k} b^{k})$ .

4 \sum k = 0 \frac{4!}{(4 - k)! k!} \cdot {(a)}^{4 - k} \cdot {(b)}^{k}

$\sum_{k = 0}^{4} \frac{4!}{(4 - k)! k!} \cdot {(a)}^{4 - k} \cdot {(b)}^{k}$

Step 2

Expand the summation.

\frac{4!}{(4 - 0)! 0!} {(a)}^{4 - 0} \cdot {(b)}^{0} + \frac{4!}{(4 - 1)! 1!} {(a)}^{4 - 1} \cdot {(b)}^{1} + \frac{4!}{(4 - 2)! 2!} {(a)}^{4 - 2} \cdot {(b)}^{2} + \frac{4!}{(4 - 3)! 3!} {(a)}^{4 - 3} \cdot {(b)}^{3} + \frac{4!}{(4 - 4)! 4!} {(a)}^{4 - 4} \cdot {(b)}^{4}

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

Step 3

Simplify the exponents for each term of the expansion.

1 \cdot {(a)}^{4} \cdot {(b)}^{0} + 4 \cdot {(a)}^{3} \cdot {(b)}^{1} + 6 \cdot {(a)}^{2} \cdot {(b)}^{2} + 4 \cdot {(a)}^{1} \cdot {(b)}^{3} + 1 \cdot {(a)}^{0} \cdot {(b)}^{4}

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

Step 4

Simplify each term.

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Step 4.1

Multiply

{(a)}^{4}

${(a)}^{4}$ by

1

$1$ .

{(a)}^{4} \cdot {(b)}^{0} + 4 \cdot {(a)}^{3} \cdot {(b)}^{1} + 6 \cdot {(a)}^{2} \cdot {(b)}^{2} + 4 \cdot {(a)}^{1} \cdot {(b)}^{3} + 1 \cdot {(a)}^{0} \cdot {(b)}^{4}

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

Step 4.2

Anything raised to

0

$0$ is

1

$1$ .

a^{4} \cdot 1 + 4 \cdot {(a)}^{3} \cdot {(b)}^{1} + 6 \cdot {(a)}^{2} \cdot {(b)}^{2} + 4 \cdot {(a)}^{1} \cdot {(b)}^{3} + 1 \cdot {(a)}^{0} \cdot {(b)}^{4}

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

Step 4.3

Multiply

a^{4}

$a^{4}$ by

1

$1$ .

a^{4} + 4 \cdot {(a)}^{3} \cdot {(b)}^{1} + 6 \cdot {(a)}^{2} \cdot {(b)}^{2} + 4 \cdot {(a)}^{1} \cdot {(b)}^{3} + 1 \cdot {(a)}^{0} \cdot {(b)}^{4}

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

Step 4.4

Simplify.

a^{4} + 4 a^{3} \cdot b + 6 \cdot {(a)}^{2} \cdot {(b)}^{2} + 4 \cdot {(a)}^{1} \cdot {(b)}^{3} + 1 \cdot {(a)}^{0} \cdot {(b)}^{4}

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

Step 4.5

Simplify.

a^{4} + 4 a^{3} b + 6 a^{2} b^{2} + 4 \cdot a \cdot {(b)}^{3} + 1 \cdot {(a)}^{0} \cdot {(b)}^{4}

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

Step 4.6

Multiply

{(a)}^{0}

${(a)}^{0}$ by

1

$1$ .

a^{4} + 4 a^{3} b + 6 a^{2} b^{2} + 4 a b^{3} + {(a)}^{0} \cdot {(b)}^{4}

$a^{4} + 4 a^{3} b + 6 a^{2} b^{2} + 4 a b^{3} + {(a)}^{0} \cdot {(b)}^{4}$

Step 4.7

Anything raised to

0

$0$ is

1

$1$ .

a^{4} + 4 a^{3} b + 6 a^{2} b^{2} + 4 a b^{3} + 1 \cdot {(b)}^{4}

$a^{4} + 4 a^{3} b + 6 a^{2} b^{2} + 4 a b^{3} + 1 \cdot {(b)}^{4}$

Step 4.8

Multiply

{(b)}^{4}

${(b)}^{4}$ by

1

$1$ .

a^{4} + 4 a^{3} b + 6 a^{2} b^{2} + 4 a b^{3} + b^{4}

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