Algebra Examples

$9 x^{3}$ , $3 x^{2} - 21 x$

Step 1

Factor $3 x$ out of $3 x^{2} - 21 x$ .

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Step 1.1

Factor $3 x$ out of $3 x^{2}$ .

$3 x (x) - 21 x$

Step 1.2

Factor $3 x$ out of $- 21 x$ .

$3 x (x) + 3 x (- 7)$

Step 1.3

Factor $3 x$ out of $3 x (x) + 3 x (- 7)$ .

$3 x (x - 7)$

Step 2

Since $9 x^{3}, 3 x (x - 7)$ contains both numbers and variables, there are four steps to find the LCM. Find LCM for the numeric, variable, and compound variable parts. Then, multiply them all together.

Steps to find the LCM for $9 x^{3}, 3 x (x - 7)$ are:

1. Find the LCM for the numeric part $9, 3$ .

2. Find the LCM for the variable part $x^{3}, x^{1}$ .

3. Find the LCM for the compound variable part $x - 7$ .

4. Multiply each LCM together.

Step 3

The LCM is the smallest positive number that all of the numbers divide into evenly.

1. List the prime factors of each number.

2. Multiply each factor the greatest number of times it occurs in either number.

Step 4

$9$ has factors of $3$ and $3$ .

$3 \cdot 3$

Step 5

Since $3$ has no factors besides $1$ and $3$ .

$3$ is a prime number

Step 6

The LCM of $9, 3$ is the result of multiplying all prime factors the greatest number of times they occur in either number.

$3 \cdot 3$

Step 7

Multiply $3$ by $3$ .

$9$

Step 8

The factors for $x^{3}$ are $x \cdot x \cdot x$ , which is $x$ multiplied by each other $3$ times.

$x^{3} = x \cdot x \cdot x$

$x$ occurs $3$ times.

Step 9

The factor for $x^{1}$ is $x$ itself.

$x^{1} = x$

$x$ occurs $1$ time.

Step 10

The LCM of $x^{3}, x^{1}$ is the result of multiplying all prime factors the greatest number of times they occur in either term.

$x \cdot x \cdot x$

Step 11

Simplify $x \cdot x \cdot x$ .

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Step 11.1

Multiply $x$ by $x$ .

$x^{2} \cdot x$

Step 11.2

Multiply $x^{2}$ by $x$ by adding the exponents.

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Step 11.2.1

Multiply $x^{2}$ by $x$ .

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Step 11.2.1.1

Raise $x$ to the power of $1$ .

$x^{2} \cdot x^{1}$

Step 11.2.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x^{2 + 1}$

Step 11.2.2

Add $2$ and $1$ .

$x^{3}$

Step 12

The factor for $x - 7$ is $x - 7$ itself.

$(x - 7) = x - 7$

$(x - 7)$ occurs $1$ time.

Step 13

The LCM of $x - 7$ is the result of multiplying all factors the greatest number of times they occur in either term.

$x - 7$

Step 14

The Least Common Multiple $LCM$ of some numbers is the smallest number that the numbers are factors of.

$9 x^{3} (x - 7)$