Trigonometry Examples

$\frac{15 x - 10 x^{2}}{4 x^{2} + 4 x + 1} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 1

Factor $5 x$ out of $15 x - 10 x^{2}$ .

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Step 1.1

Factor $5 x$ out of $15 x$ .

$\frac{5 x (3) - 10 x^{2}}{4 x^{2} + 4 x + 1} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 1.2

Factor $5 x$ out of $- 10 x^{2}$ .

$\frac{5 x (3) + 5 x (- 2 x)}{4 x^{2} + 4 x + 1} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 1.3

Factor $5 x$ out of $5 x (3) + 5 x (- 2 x)$ .

$\frac{5 x (3 - 2 x)}{4 x^{2} + 4 x + 1} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 2

Factor using the perfect square rule.

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Step 2.1

Rewrite $4 x^{2}$ as ${(2 x)}^{2}$ .

$\frac{5 x (3 - 2 x)}{{(2 x)}^{2} + 4 x + 1} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 2.2

Rewrite $1$ as $1^{2}$ .

$\frac{5 x (3 - 2 x)}{{(2 x)}^{2} + 4 x + 1^{2}} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 2.3

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

$4 x = 2 \cdot (2 x) \cdot 1$

Step 2.4

Rewrite the polynomial.

$\frac{5 x (3 - 2 x)}{{(2 x)}^{2} + 2 \cdot (2 x) \cdot 1 + 1^{2}} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 2.5

Factor using the perfect square trinomial rule $a^{2} + 2 a b + b^{2} = {(a + b)}^{2}$ , where $a = 2 x$ and $b = 1$ .

$\frac{5 x (3 - 2 x)}{{(2 x + 1)}^{2}} \cdot \frac{4 x^{2} + 8 + 3}{4 x^{2} - 9}$

Step 3

Add $8$ and $3$ .

$\frac{5 x (3 - 2 x)}{{(2 x + 1)}^{2}} \cdot \frac{4 x^{2} + 11}{4 x^{2} - 9}$

Step 4

Simplify the denominator.

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Step 4.1

Rewrite $4 x^{2}$ as ${(2 x)}^{2}$ .

$\frac{5 x (3 - 2 x)}{{(2 x + 1)}^{2}} \cdot \frac{4 x^{2} + 11}{{(2 x)}^{2} - 9}$

Step 4.2

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

$\frac{5 x (3 - 2 x)}{{(2 x + 1)}^{2}} \cdot \frac{4 x^{2} + 11}{{(2 x)}^{2} - 3^{2}}$

Step 4.3

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

$\frac{5 x (3 - 2 x)}{{(2 x + 1)}^{2}} \cdot \frac{4 x^{2} + 11}{(2 x + 3) (2 x - 3)}$

Step 5

Simplify terms.

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Step 5.1

Multiply $\frac{5 x (3 - 2 x)}{{(2 x + 1)}^{2}}$ by $\frac{4 x^{2} + 11}{(2 x + 3) (2 x - 3)}$ .

$\frac{5 x (3 - 2 x) (4 x^{2} + 11)}{{(2 x + 1)}^{2} ((2 x + 3) (2 x - 3))}$

Step 5.2

Cancel the common factor of $3 - 2 x$ and $2 x - 3$ .

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Step 5.2.1

Rewrite $3$ as $- 1 (- 3)$ .

$\frac{5 x (- 1 (- 3) - 2 x) (4 x^{2} + 11)}{{(2 x + 1)}^{2} ((2 x + 3) (2 x - 3))}$

Step 5.2.2

Factor $- 1$ out of $- 2 x$ .

$\frac{5 x (- 1 (- 3) - (2 x)) (4 x^{2} + 11)}{{(2 x + 1)}^{2} ((2 x + 3) (2 x - 3))}$

Step 5.2.3

Factor $- 1$ out of $- 1 (- 3) - (2 x)$ .

$\frac{5 x (- 1 (- 3 + 2 x)) (4 x^{2} + 11)}{{(2 x + 1)}^{2} ((2 x + 3) (2 x - 3))}$

Step 5.2.4

Reorder terms.

$\frac{5 x (- 1 (2 x - 3)) (4 x^{2} + 11)}{{(2 x + 1)}^{2} (2 x + 3) (2 x - 3)}$

Step 5.2.5

Cancel the common factor.

$\frac{5 x (- 1 (2 x - 3)) (4 x^{2} + 11)}{{(2 x + 1)}^{2} (2 x + 3) (2 x - 3)}$

Step 5.2.6

Rewrite the expression.

$\frac{5 x \cdot (- 1) (4 x^{2} + 11)}{{(2 x + 1)}^{2} (2 x + 3)}$

Step 5.3

Simplify the expression.

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Step 5.3.1

Multiply $- 1$ by $5$ .

$\frac{- 5 x (4 x^{2} + 11)}{{(2 x + 1)}^{2} (2 x + 3)}$

Step 5.3.2

Move the negative in front of the fraction.

$- \frac{5 x (4 x^{2} + 11)}{{(2 x + 1)}^{2} (2 x + 3)}$