Precalculus Examples

${(1 + i)}^{20}$

Step 1

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

$\sum_{k = 0}^{20} \frac{20!}{(20 - k)! k!} \cdot {(1)}^{20 - k} \cdot {(i)}^{k}$

Step 2

Expand the summation.

$\frac{20!}{(20 - 0)! 0!} \cdot {(1)}^{20 - 0} \cdot {(i)}^{0} + \frac{20!}{(20 - 1)! 1!} \cdot {(1)}^{20 - 1} \cdot {(i)}^{1} + \dots + \frac{20!}{(20 - 20)! 20!} \cdot {(1)}^{20 - 20} \cdot {(i)}^{20}$

Step 3

Simplify the exponents for each term of the expansion.

$1 \cdot {(1)}^{20} \cdot {(i)}^{0} + 20 \cdot {(1)}^{19} \cdot {(i)}^{1} + \dots + 1 \cdot {(1)}^{0} \cdot {(i)}^{20}$

Step 4

Simplify the polynomial result.

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