Algebra Examples

${(x - 3)}^{3}$

Step 1

Pascal's Triangle can be displayed as such:

$1$

$1 - 1$

$1 - 2 - 1$

$1 - 3 - 3 - 1$

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 ${(x - 3)}^{3}$ , $n = 3$ so the coefficients of the expansion will correspond with line $4$ .

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 $1 - 3 - 3 - 1$ .

$1 a^{3} b^{0} + 3 a^{2} b + 3 a b^{2} + 1 a^{0} b^{3}$

Step 3

Substitute the actual values of $a$ $x$ and $b$ $- 3$ into the expression.

$1 {(x)}^{3} {(- 3)}^{0} + 3 {(x)}^{2} {(- 3)}^{1} + 3 {(x)}^{1} {(- 3)}^{2} + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4

Simplify each term.

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Step 4.1

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

${(x)}^{3} {(- 3)}^{0} + 3 {(x)}^{2} {(- 3)}^{1} + 3 {(x)}^{1} {(- 3)}^{2} + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.2

Anything raised to $0$ is $1$ .

$x^{3} \cdot 1 + 3 {(x)}^{2} {(- 3)}^{1} + 3 {(x)}^{1} {(- 3)}^{2} + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.3

Multiply $x^{3}$ by $1$ .

$x^{3} + 3 {(x)}^{2} {(- 3)}^{1} + 3 {(x)}^{1} {(- 3)}^{2} + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.4

Evaluate the exponent.

$x^{3} + 3 x^{2} \cdot - 3 + 3 {(x)}^{1} {(- 3)}^{2} + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.5

Multiply $- 3$ by $3$ .

$x^{3} - 9 x^{2} + 3 {(x)}^{1} {(- 3)}^{2} + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.6

Simplify.

$x^{3} - 9 x^{2} + 3 x {(- 3)}^{2} + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.7

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

$x^{3} - 9 x^{2} + 3 x \cdot 9 + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.8

Multiply $9$ by $3$ .

$x^{3} - 9 x^{2} + 27 x + 1 {(x)}^{0} {(- 3)}^{3}$

Step 4.9

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

$x^{3} - 9 x^{2} + 27 x + {(x)}^{0} {(- 3)}^{3}$

Step 4.10

Anything raised to $0$ is $1$ .

$x^{3} - 9 x^{2} + 27 x + 1 {(- 3)}^{3}$

Step 4.11

Multiply ${(- 3)}^{3}$ by $1$ .

$x^{3} - 9 x^{2} + 27 x + {(- 3)}^{3}$

Step 4.12

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

$x^{3} - 9 x^{2} + 27 x - 27$