Calculus Examples

$1 - \frac{x^{2}}{6} < \frac{x \sin (x)}{2 - 2 \cos (x)} < 1$

Step 1

Factor $2$ out of $2 - 2 \cos (x)$ .

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Step 1.1

Factor $2$ out of $2$ .

$1 - \frac{x^{2}}{6} < \frac{x \sin (x)}{2 (1) - 2 \cos (x)} < 1$

Step 1.2

Factor $2$ out of $- 2 \cos (x)$ .

$1 - \frac{x^{2}}{6} < \frac{x \sin (x)}{2 (1) + 2 (- \cos (x))} < 1$

Step 1.3

Factor $2$ out of $2 (1) + 2 (- \cos (x))$ .

$1 - \frac{x^{2}}{6} < \frac{x \sin (x)}{2 (1 - \cos (x))} < 1$

Step 2

Multiply each term in the inequality by $2 (1 - \cos (x))$ .

$1 (2 (1 - \cos (x))) - \frac{x^{2}}{6} (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3

Simplify each term.

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Step 3.1

Multiply $2 (1 - \cos (x))$ by $1$ .

$2 (1 - \cos (x)) - \frac{x^{2}}{6} \cdot (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.2

Apply the distributive property.

$2 \cdot 1 + 2 (- \cos (x)) - \frac{x^{2}}{6} \cdot (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.3

Multiply $2$ by $1$ .

$2 + 2 (- \cos (x)) - \frac{x^{2}}{6} \cdot (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.4

Multiply $- 1$ by $2$ .

$2 - 2 \cos (x) - \frac{x^{2}}{6} \cdot (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.5

Cancel the common factor of $2$ .

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Step 3.5.1

Move the leading negative in $- \frac{x^{2}}{6}$ into the numerator.

$2 - 2 \cos (x) + \frac{- x^{2}}{6} \cdot (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.5.2

Factor $2$ out of $6$ .

$2 - 2 \cos (x) + \frac{- x^{2}}{2 (3)} \cdot (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.5.3

Cancel the common factor.

$2 - 2 \cos (x) + \frac{- x^{2}}{2 \cdot 3} \cdot (2 (1 - \cos (x))) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.5.4

Rewrite the expression.

$2 - 2 \cos (x) + \frac{- x^{2}}{3} \cdot (1 - \cos (x)) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.6

Move the negative in front of the fraction.

$2 - 2 \cos (x) - \frac{x^{2}}{3} \cdot (1 - \cos (x)) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.7

Apply the distributive property.

$2 - 2 \cos (x) - \frac{x^{2}}{3} \cdot 1 - \frac{x^{2}}{3} \cdot (- \cos (x)) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.8

Multiply $- 1$ by $1$ .

$2 - 2 \cos (x) - \frac{x^{2}}{3} - \frac{x^{2}}{3} \cdot (- \cos (x)) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.9

Multiply $- \frac{x^{2}}{3} (- \cos (x))$ .

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Step 3.9.1

Multiply $- 1$ by $- 1$ .

$2 - 2 \cos (x) - \frac{x^{2}}{3} + 1 (\frac{x^{2}}{3}) \cdot \cos (x) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.9.2

Multiply $\frac{x^{2}}{3}$ by $1$ .

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2}}{3} \cdot \cos (x) < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 3.9.3

Combine $\frac{x^{2}}{3}$ and $\cos (x)$ .

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < \frac{x \sin (x)}{2 (1 - \cos (x))} \cdot (2 (1 - \cos (x))) < 1 (2 (1 - \cos (x)))$

Step 4

Rewrite using the commutative property of multiplication.

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < 2 (\frac{x \sin (x)}{2 (1 - \cos (x))}) \cdot (1 - \cos (x)) < 1 (2 (1 - \cos (x)))$

Step 5

Cancel the common factor of $2$ .

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Step 5.1

Cancel the common factor.

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < 2 (\frac{x \sin (x)}{2 (1 - \cos (x))}) \cdot (1 - \cos (x)) < 1 (2 (1 - \cos (x)))$

Step 5.2

Rewrite the expression.

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < \frac{x \sin (x)}{1 - \cos (x)} \cdot (1 - \cos (x)) < 1 (2 (1 - \cos (x)))$

Step 6

Cancel the common factor of $1 - \cos (x)$ .

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Step 6.1

Cancel the common factor.

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < \frac{x \sin (x)}{1 - \cos (x)} \cdot (1 - \cos (x)) < 1 (2 (1 - \cos (x)))$

Step 6.2

Rewrite the expression.

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < x \sin (x) < 1 (2 (1 - \cos (x)))$

Step 7

Multiply $2 (1 - \cos (x))$ by $1$ .

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < x \sin (x) < 2 (1 - \cos (x))$

Step 8

Apply the distributive property.

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < x \sin (x) < 2 \cdot 1 + 2 (- \cos (x))$

Step 9

Multiply.

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Step 9.1

Multiply $2$ by $1$ .

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < x \sin (x) < 2 + 2 (- \cos (x))$

Step 9.2

Multiply $- 1$ by $2$ .

$2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3} < x \sin (x) < 2 - 2 \cos (x)$

Step 10

Convert the inequality to interval notation.

$(2 - 2 \cos (x) - \frac{x^{2}}{3} + \frac{x^{2} \cos (x)}{3}, 2 - 2 \cos (x))$

Step 11