Calculus Examples

$f (x) = \frac{7 x}{4 - \tan (x)}$

Step 1

Since $7$ is constant with respect to $x$ , the derivative of $\frac{7 x}{4 - \tan (x)}$ with respect to $x$ is $7 \frac{d}{d x} [\frac{x}{4 - \tan (x)}]$ .

$7 \frac{d}{d x} [\frac{x}{4 - \tan (x)}]$

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 $f (x) = x$ and $g (x) = 4 - \tan (x)$ .

$7 \frac{(4 - \tan (x)) \frac{d}{d x} [x] - x \frac{d}{d x} [4 - \tan (x)]}{{(4 - \tan (x))}^{2}}$

Step 3

Differentiate.

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Step 3.1

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

$7 \frac{(4 - \tan (x)) \cdot 1 - x \frac{d}{d x} [4 - \tan (x)]}{{(4 - \tan (x))}^{2}}$

Step 3.2

Multiply $4 - \tan (x)$ by $1$ .

$7 \frac{4 - \tan (x) - x \frac{d}{d x} [4 - \tan (x)]}{{(4 - \tan (x))}^{2}}$

Step 3.3

By the Sum Rule, the derivative of $4 - \tan (x)$ with respect to $x$ is $\frac{d}{d x} [4] + \frac{d}{d x} [- \tan (x)]$ .

$7 \frac{4 - \tan (x) - x (\frac{d}{d x} [4] + \frac{d}{d x} [- \tan (x)])}{{(4 - \tan (x))}^{2}}$

Step 3.4

Since $4$ is constant with respect to $x$ , the derivative of $4$ with respect to $x$ is $0$ .

$7 \frac{4 - \tan (x) - x (0 + \frac{d}{d x} [- \tan (x)])}{{(4 - \tan (x))}^{2}}$

Step 3.5

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

$7 \frac{4 - \tan (x) - x \frac{d}{d x} [- \tan (x)]}{{(4 - \tan (x))}^{2}}$

Step 3.6

Since $- 1$ is constant with respect to $x$ , the derivative of $- \tan (x)$ with respect to $x$ is $- \frac{d}{d x} [\tan (x)]$ .

$7 \frac{4 - \tan (x) - x (- \frac{d}{d x} [\tan (x)])}{{(4 - \tan (x))}^{2}}$

Step 3.7

Multiply.

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Step 3.7.1

Multiply $- 1$ by $- 1$ .

$7 \frac{4 - \tan (x) + 1 x \frac{d}{d x} [\tan (x)]}{{(4 - \tan (x))}^{2}}$

Step 3.7.2

Multiply $x$ by $1$ .

$7 \frac{4 - \tan (x) + x \frac{d}{d x} [\tan (x)]}{{(4 - \tan (x))}^{2}}$

Step 4

The derivative of $\tan (x)$ with respect to $x$ is $\sec^{2} (x)$ .

$7 \frac{4 - \tan (x) + x \sec^{2} (x)}{{(4 - \tan (x))}^{2}}$

Step 5

Combine $7$ and $\frac{4 - \tan (x) + x \sec^{2} (x)}{{(4 - \tan (x))}^{2}}$ .

$\frac{7 (4 - \tan (x) + x \sec^{2} (x))}{{(4 - \tan (x))}^{2}}$

Step 6

Simplify.

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Step 6.1

Apply the distributive property.

$\frac{7 \cdot 4 + 7 (- \tan (x)) + 7 (x \sec^{2} (x))}{{(4 - \tan (x))}^{2}}$

Step 6.2

Simplify each term.

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Step 6.2.1

Multiply $7$ by $4$ .

$\frac{28 + 7 (- \tan (x)) + 7 (x \sec^{2} (x))}{{(4 - \tan (x))}^{2}}$

Step 6.2.2

Multiply $- 1$ by $7$ .

$\frac{28 - 7 \tan (x) + 7 x \sec^{2} (x)}{{(4 - \tan (x))}^{2}}$

Step 6.3

Reorder terms.

$\frac{7 x \sec^{2} (x) + 28 - 7 \tan (x)}{{(4 - \tan (x))}^{2}}$

Step 6.4

Factor $7$ out of $7 x \sec^{2} (x) + 28 - 7 \tan (x)$ .

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Step 6.4.1

Factor $7$ out of $7 x \sec^{2} (x)$ .

$\frac{7 (x \sec^{2} (x)) + 28 - 7 \tan (x)}{{(4 - \tan (x))}^{2}}$

Step 6.4.2

Factor $7$ out of $28$ .

$\frac{7 (x \sec^{2} (x)) + 7 (4) - 7 \tan (x)}{{(4 - \tan (x))}^{2}}$

Step 6.4.3

Factor $7$ out of $- 7 \tan (x)$ .

$\frac{7 (x \sec^{2} (x)) + 7 (4) + 7 (- \tan (x))}{{(4 - \tan (x))}^{2}}$

Step 6.4.4

Factor $7$ out of $7 (x \sec^{2} (x)) + 7 (4)$ .

$\frac{7 (x \sec^{2} (x) + 4) + 7 (- \tan (x))}{{(4 - \tan (x))}^{2}}$

Step 6.4.5

Factor $7$ out of $7 (x \sec^{2} (x) + 4) + 7 (- \tan (x))$ .

$\frac{7 (x \sec^{2} (x) + 4 - \tan (x))}{{(4 - \tan (x))}^{2}}$