Algebra Examples

$2 x^{2} - 18$ and $5 x^{3} + 30 x^{2} + 45 x$

Step 1

Factor $2 x^{2} - 18$ .

Tap for more steps...

Step 1.1

Factor $2$ out of $2 x^{2} - 18$ .

Tap for more steps...

Step 1.1.1

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

$2 (x^{2}) - 18$

Step 1.1.2

Factor $2$ out of $- 18$ .

$2 x^{2} + 2 \cdot - 9$

Step 1.1.3

Factor $2$ out of $2 x^{2} + 2 \cdot - 9$ .

$2 (x^{2} - 9)$

Step 1.2

Rewrite $9$ as $3^{2}$ .

$2 (x^{2} - 3^{2})$

Step 1.3

Factor.

Tap for more steps...

Step 1.3.1

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = x$ and $b = 3$ .

$2 ((x + 3) (x - 3))$

Step 1.3.2

Remove unnecessary parentheses.

$2 (x + 3) (x - 3)$

Step 2

Factor $5 x^{3} + 30 x^{2} + 45 x$ .

Tap for more steps...

Step 2.1

Factor $5 x$ out of $5 x^{3} + 30 x^{2} + 45 x$ .

Tap for more steps...

Step 2.1.1

Factor $5 x$ out of $5 x^{3}$ .

$5 x (x^{2}) + 30 x^{2} + 45 x$

Step 2.1.2

Factor $5 x$ out of $30 x^{2}$ .

$5 x (x^{2}) + 5 x (6 x) + 45 x$

Step 2.1.3

Factor $5 x$ out of $45 x$ .

$5 x (x^{2}) + 5 x (6 x) + 5 x (9)$

Step 2.1.4

Factor $5 x$ out of $5 x (x^{2}) + 5 x (6 x)$ .

$5 x (x^{2} + 6 x) + 5 x (9)$

Step 2.1.5

Factor $5 x$ out of $5 x (x^{2} + 6 x) + 5 x (9)$ .

$5 x (x^{2} + 6 x + 9)$

Step 2.2

Factor using the perfect square rule.

Tap for more steps...

Step 2.2.1

Rewrite $9$ as $3^{2}$ .

$5 x (x^{2} + 6 x + 3^{2})$

Step 2.2.2

Check that the middle term is two times the product of the numbers being squared in the first term and third term.

$6 x = 2 \cdot x \cdot 3$

Step 2.2.3

Rewrite the polynomial.

$5 x (x^{2} + 2 \cdot x \cdot 3 + 3^{2})$

Step 2.2.4

Factor using the perfect square trinomial rule $a^{2} + 2 a b + b^{2} = {(a + b)}^{2}$ , where $a = x$ and $b = 3$ .

$5 x {(x + 3)}^{2}$

Step 3

Since $2 (x + 3) (x - 3), 5 x {(x + 3)}^{2}$ 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 $2 (x + 3) (x - 3), 5 x {(x + 3)}^{2}$ are:

1. Find the LCM for the numeric part $2, 5$ .

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

3. Find the LCM for the compound variable part $x + 3, x - 3, {(x + 3)}^{2}$ .

4. Multiply each LCM together.

Step 4

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 5

Since $2$ has no factors besides $1$ and $2$ .

$2$ is a prime number

Step 6

Since $5$ has no factors besides $1$ and $5$ .

$5$ is a prime number

Step 7

The LCM of $2, 5$ is the result of multiplying all prime factors the greatest number of times they occur in either number.

$2 \cdot 5$

Step 8

Multiply $2$ by $5$ .

$10$

Step 9

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

$x^{1} = x$

$x$ occurs $1$ time.

Step 10

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

$x$

Step 11

The factor for $x + 3$ is $x + 3$ itself.

$(x + 3) = x + 3$

$(x + 3)$ occurs $1$ time.

Step 12

The factor for $x - 3$ is $x - 3$ itself.

$(x - 3) = x - 3$

$(x - 3)$ occurs $1$ time.

Step 13

The factors for $x + 3$ are $(x + 3) \cdot (x + 3)$ , which is $x + 3$ multiplied by itself $2$ times.

$(x + 3) = (x + 3) \cdot (x + 3)$

$(x + 3)$ occurs $2$ times.

Step 14

The LCM of $x + 3, x - 3, {(x + 3)}^{2}$ is the result of multiplying all factors the greatest number of times they occur in either term.

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

Step 15

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

$10 x {(x + 3)}^{2} (x - 3)$