Calculus Examples

$y = \frac{2 x \sin (x)}{1 + \cos (x)}$

Step 1

Since $2$ is constant with respect to $x$ , the derivative of $\frac{2 x \sin (x)}{1 + \cos (x)}$ with respect to $x$ is $2 \frac{d}{d x} [\frac{x \sin (x)}{1 + \cos (x)}]$ .

$2 \frac{d}{d x} [\frac{x \sin (x)}{1 + \cos (x)}]$

Step 2

Differentiate using the Quotient Rule which states that $\frac{d}{d x} [\frac{f (x)}{g (x)}]$ is $\frac{g (x) \frac{d}{d x} [f (x)] - f (x) \frac{d}{d x} [g (x)]}{{g (x)}^{2}}$ where $f (x) = x \sin (x)$ and $g (x) = 1 + \cos (x)$ .

$2 \frac{(1 + \cos (x)) \frac{d}{d x} [x \sin (x)] - x \sin (x) \frac{d}{d x} [1 + \cos (x)]}{{(1 + \cos (x))}^{2}}$

Step 3

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x$ and $g (x) = \sin (x)$ .

$2 \frac{(1 + \cos (x)) (x \frac{d}{d x} [\sin (x)] + \sin (x) \frac{d}{d x} [x]) - x \sin (x) \frac{d}{d x} [1 + \cos (x)]}{{(1 + \cos (x))}^{2}}$

Step 4

The derivative of $\sin (x)$ with respect to $x$ is $\cos (x)$ .

$2 \frac{(1 + \cos (x)) (x \cos (x) + \sin (x) \frac{d}{d x} [x]) - x \sin (x) \frac{d}{d x} [1 + \cos (x)]}{{(1 + \cos (x))}^{2}}$

Step 5

Differentiate.

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Step 5.1

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$2 \frac{(1 + \cos (x)) (x \cos (x) + \sin (x) \cdot 1) - x \sin (x) \frac{d}{d x} [1 + \cos (x)]}{{(1 + \cos (x))}^{2}}$

Step 5.2

Multiply $\sin (x)$ by $1$ .

$2 \frac{(1 + \cos (x)) (x \cos (x) + \sin (x)) - x \sin (x) \frac{d}{d x} [1 + \cos (x)]}{{(1 + \cos (x))}^{2}}$

Step 5.3

By the Sum Rule, the derivative of $1 + \cos (x)$ with respect to $x$ is $\frac{d}{d x} [1] + \frac{d}{d x} [\cos (x)]$ .

$2 \frac{(1 + \cos (x)) (x \cos (x) + \sin (x)) - x \sin (x) (\frac{d}{d x} [1] + \frac{d}{d x} [\cos (x)])}{{(1 + \cos (x))}^{2}}$

Step 5.4

Since $1$ is constant with respect to $x$ , the derivative of $1$ with respect to $x$ is $0$ .

$2 \frac{(1 + \cos (x)) (x \cos (x) + \sin (x)) - x \sin (x) (0 + \frac{d}{d x} [\cos (x)])}{{(1 + \cos (x))}^{2}}$

Step 5.5

Add $0$ and $\frac{d}{d x} [\cos (x)]$ .

$2 \frac{(1 + \cos (x)) (x \cos (x) + \sin (x)) - x \sin (x) \frac{d}{d x} [\cos (x)]}{{(1 + \cos (x))}^{2}}$

Step 6

The derivative of $\cos (x)$ with respect to $x$ is $- \sin (x)$ .

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

Step 7

Multiply.

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Step 7.1

Multiply $- 1$ by $- 1$ .

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

Step 7.2

Multiply $x$ by $1$ .

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

Step 8

Raise $\sin (x)$ to the power of $1$ .

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

Step 9

Raise $\sin (x)$ to the power of $1$ .

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

Step 10

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

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

Step 11

Add $1$ and $1$ .

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

Step 12

Combine $2$ and $\frac{(1 + \cos (x)) (x \cos (x) + \sin (x)) + x \sin^{2} (x)}{{(1 + \cos (x))}^{2}}$ .

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

Step 13

Simplify.

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Step 13.1

Apply the distributive property.

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

Step 13.2

Simplify the numerator.

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Step 13.2.1

Simplify each term.

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Step 13.2.1.1

Expand $(1 + \cos (x)) (x \cos (x) + \sin (x))$ using the FOIL Method.

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Step 13.2.1.1.1

Apply the distributive property.

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

Step 13.2.1.1.2

Apply the distributive property.

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

Step 13.2.1.1.3

Apply the distributive property.

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

Step 13.2.1.2

Simplify each term.

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Step 13.2.1.2.1

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

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

Step 13.2.1.2.2

Multiply $\sin (x)$ by $1$ .

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

Step 13.2.1.2.3

Multiply $\cos (x) (x \cos (x))$ .

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Step 13.2.1.2.3.1

Raise $\cos (x)$ to the power of $1$ .

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

Step 13.2.1.2.3.2

Raise $\cos (x)$ to the power of $1$ .

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

Step 13.2.1.2.3.3

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

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

Step 13.2.1.2.3.4

Add $1$ and $1$ .

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

Step 13.2.1.3

Apply the distributive property.

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

Step 13.2.1.4

Simplify.

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Step 13.2.1.4.1

Reorder $2 \cos (x)$ and $\sin (x)$ .

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

Step 13.2.1.4.2

Reorder $\sin (x)$ and $2$ .

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

Step 13.2.1.4.3

Apply the sine double-angle identity.

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

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

Step 13.2.2

Move $2 x \sin^{2} (x)$ .

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

Step 13.2.3

Factor $2 x$ out of $2 x \cos^{2} (x)$ .

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

Step 13.2.4

Factor $2 x$ out of $2 x \sin^{2} (x)$ .

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

Step 13.2.5

Factor $2 x$ out of $2 x (\cos^{2} (x)) + 2 x (\sin^{2} (x))$ .

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

Step 13.2.6

Rearrange terms.

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

Step 13.2.7

Apply pythagorean identity.

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

Step 13.2.8

Multiply $2$ by $1$ .

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

Step 13.3

Reorder terms.

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