Precalculus Examples

${(a - \sqrt{2})}^{8}$

Step 1

Pascal's Triangle can be displayed as such:

$1$

$1 - 1$

$1 - 2 - 1$

$\dots$

$1 - 6 - 15 - 20 - 15 - 6 - 1$

$1 - 7 - 21 - 35 - 35 - 21 - 7 - 1$

$1 - 8 - 28 - 56 - 70 - 56 - 28 - 8 - 1$

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 ${(a - \sqrt{2})}^{8}$ , $n = 8$ so the coefficients of the expansion will correspond with line $9$ .

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 $1 - 8 - 28 - 56 - 70 - 56 - 28 - 8 - 1$ .

$1 a^{8} b^{0} + 8 a^{7} b + 28 a^{6} b^{2} + 56 a^{5} b^{3} + 70 a^{4} b^{4} + 56 a^{3} b^{5} + 28 a^{2} b^{6} + 8 a b^{7} + 1 a^{0} b^{8}$

Step 3

Substitute the actual values of $a$ $a$ and $b$ $- 1.41421356$ into the expression.

$1 {(a)}^{8} {(- 1.41421356)}^{0} + 8 {(a)}^{7} {(- 1.41421356)}^{1} + 28 {(a)}^{6} {(- 1.41421356)}^{2} + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4

Simplify each term.

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Step 4.1

Multiply ${(a)}^{8}$ by $1$ .

${(a)}^{8} {(- 1.41421356)}^{0} + 8 {(a)}^{7} {(- 1.41421356)}^{1} + 28 {(a)}^{6} {(- 1.41421356)}^{2} + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.2

Anything raised to $0$ is $1$ .

$a^{8} \cdot 1 + 8 {(a)}^{7} {(- 1.41421356)}^{1} + 28 {(a)}^{6} {(- 1.41421356)}^{2} + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.3

Multiply $a^{8}$ by $1$ .

$a^{8} + 8 {(a)}^{7} {(- 1.41421356)}^{1} + 28 {(a)}^{6} {(- 1.41421356)}^{2} + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.4

Evaluate the exponent.

$a^{8} + 8 a^{7} \cdot - 1.41421356 + 28 {(a)}^{6} {(- 1.41421356)}^{2} + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.5

Multiply $- 1.41421356$ by $8$ .

$a^{8} - 11.31370849 a^{7} + 28 {(a)}^{6} {(- 1.41421356)}^{2} + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.6

Raise $- 1.41421356$ to the power of $2$ .

$a^{8} - 11.31370849 a^{7} + 28 a^{6} \cdot 2 + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.7

Multiply $2$ by $28$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} + 56 {(a)}^{5} {(- 1.41421356)}^{3} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.8

Raise $- 1.41421356$ to the power of $3$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} + 56 a^{5} \cdot - 2.82842712 + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.9

Multiply $- 2.82842712$ by $56$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 70 {(a)}^{4} {(- 1.41421356)}^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.10

Raise $- 1.41421356$ to the power of $4$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 70 a^{4} \cdot 4 + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.11

Multiply $4$ by $70$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} + 56 {(a)}^{3} {(- 1.41421356)}^{5} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.12

Raise $- 1.41421356$ to the power of $5$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} + 56 a^{3} \cdot - 5.65685424 + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.13

Multiply $- 5.65685424$ by $56$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 28 {(a)}^{2} {(- 1.41421356)}^{6} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.14

Raise $- 1.41421356$ to the power of $6$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 28 a^{2} \cdot 8 + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.15

Multiply $8$ by $28$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} + 8 {(a)}^{1} {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.16

Simplify.

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} + 8 a {(- 1.41421356)}^{7} + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.17

Raise $- 1.41421356$ to the power of $7$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} + 8 a \cdot - 11.31370849 + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.18

Multiply $- 11.31370849$ by $8$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} - 90.50966799 a + 1 {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.19

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

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} - 90.50966799 a + {(a)}^{0} {(- 1.41421356)}^{8}$

Step 4.20

Anything raised to $0$ is $1$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} - 90.50966799 a + 1 {(- 1.41421356)}^{8}$

Step 4.21

Multiply ${(- 1.41421356)}^{8}$ by $1$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} - 90.50966799 a + {(- 1.41421356)}^{8}$

Step 4.22

Raise $- 1.41421356$ to the power of $8$ .

$a^{8} - 11.31370849 a^{7} + 56 a^{6} - 158.39191898 a^{5} + 280 a^{4} - 316.78383797 a^{3} + 224 a^{2} - 90.50966799 a + 16$