Calculus Examples

$\ln (\sec (2 x) + 6 \tan (x))$

Step 1

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \ln (x)$ and $g (x) = \sec (2 x) + 6 \tan (x)$ .

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Step 1.1

To apply the Chain Rule, set $u_{1}$ as $\sec (2 x) + 6 \tan (x)$ .

$\frac{d}{d u_{1}} [\ln (u_{1})] \frac{d}{d x} [\sec (2 x) + 6 \tan (x)]$

Step 1.2

The derivative of $\ln (u_{1})$ with respect to $u_{1}$ is $\frac{1}{u_{1}}$ .

$\frac{1}{u_{1}} \frac{d}{d x} [\sec (2 x) + 6 \tan (x)]$

Step 1.3

Replace all occurrences of $u_{1}$ with $\sec (2 x) + 6 \tan (x)$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} \frac{d}{d x} [\sec (2 x) + 6 \tan (x)]$

Step 2

By the Sum Rule, the derivative of $\sec (2 x) + 6 \tan (x)$ with respect to $x$ is $\frac{d}{d x} [\sec (2 x)] + \frac{d}{d x} [6 \tan (x)]$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} (\frac{d}{d x} [\sec (2 x)] + \frac{d}{d x} [6 \tan (x)])$

Step 3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \sec (x)$ and $g (x) = 2 x$ .

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Step 3.1

To apply the Chain Rule, set $u_{2}$ as $2 x$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} (\frac{d}{d u_{2}} [\sec (u_{2})] \frac{d}{d x} [2 x] + \frac{d}{d x} [6 \tan (x)])$

Step 3.2

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

$\frac{1}{\sec (2 x) + 6 \tan (x)} (\sec (u_{2}) \tan (u_{2}) \frac{d}{d x} [2 x] + \frac{d}{d x} [6 \tan (x)])$

Step 3.3

Replace all occurrences of $u_{2}$ with $2 x$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} (\sec (2 x) \tan (2 x) \frac{d}{d x} [2 x] + \frac{d}{d x} [6 \tan (x)])$

Step 4

Differentiate.

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Step 4.1

Since $2$ is constant with respect to $x$ , the derivative of $2 x$ with respect to $x$ is $2 \frac{d}{d x} [x]$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} (\sec (2 x) \tan (2 x) (2 \frac{d}{d x} [x]) + \frac{d}{d x} [6 \tan (x)])$

Step 4.2

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

$\frac{1}{\sec (2 x) + 6 \tan (x)} (\sec (2 x) \tan (2 x) (2 \cdot 1) + \frac{d}{d x} [6 \tan (x)])$

Step 4.3

Simplify the expression.

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Step 4.3.1

Multiply $2$ by $1$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} (\sec (2 x) \tan (2 x) \cdot 2 + \frac{d}{d x} [6 \tan (x)])$

Step 4.3.2

Move $2$ to the left of $\sec (2 x) \tan (2 x)$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} (2 \cdot (\sec (2 x) \tan (2 x)) + \frac{d}{d x} [6 \tan (x)])$

Step 4.4

Since $6$ is constant with respect to $x$ , the derivative of $6 \tan (x)$ with respect to $x$ is $6 \frac{d}{d x} [\tan (x)]$ .

$\frac{1}{\sec (2 x) + 6 \tan (x)} (2 \sec (2 x) \tan (2 x) + 6 \frac{d}{d x} [\tan (x)])$

Step 5

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

$\frac{1}{\sec (2 x) + 6 \tan (x)} (2 \sec (2 x) \tan (2 x) + 6 \sec^{2} (x))$

Step 6

Simplify.

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Step 6.1

Reorder the factors of $\frac{1}{\sec (2 x) + 6 \tan (x)} (2 \sec (2 x) \tan (2 x) + 6 \sec^{2} (x))$ .

$(2 \sec (2 x) \tan (2 x) + 6 \sec^{2} (x)) \frac{1}{\sec (2 x) + 6 \tan (x)}$

Step 6.2

Apply the distributive property.

$2 \sec (2 x) \tan (2 x) \frac{1}{\sec (2 x) + 6 \tan (x)} + 6 \sec^{2} (x) \frac{1}{\sec (2 x) + 6 \tan (x)}$

Step 6.3

Multiply $2 \sec (2 x) \tan (2 x) \frac{1}{\sec (2 x) + 6 \tan (x)}$ .

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Step 6.3.1

Combine $\frac{1}{\sec (2 x) + 6 \tan (x)}$ and $2$ .

$\frac{2}{\sec (2 x) + 6 \tan (x)} \sec (2 x) \tan (2 x) + 6 \sec^{2} (x) \frac{1}{\sec (2 x) + 6 \tan (x)}$

Step 6.3.2

Combine $\frac{2}{\sec (2 x) + 6 \tan (x)}$ and $\sec (2 x)$ .

$\frac{2 \sec (2 x)}{\sec (2 x) + 6 \tan (x)} \tan (2 x) + 6 \sec^{2} (x) \frac{1}{\sec (2 x) + 6 \tan (x)}$

Step 6.3.3

Combine $\frac{2 \sec (2 x)}{\sec (2 x) + 6 \tan (x)}$ and $\tan (2 x)$ .

$\frac{2 \sec (2 x) \tan (2 x)}{\sec (2 x) + 6 \tan (x)} + 6 \sec^{2} (x) \frac{1}{\sec (2 x) + 6 \tan (x)}$

Step 6.4

Multiply $6 \sec^{2} (x) \frac{1}{\sec (2 x) + 6 \tan (x)}$ .

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Step 6.4.1

Combine $\frac{1}{\sec (2 x) + 6 \tan (x)}$ and $6$ .

$\frac{2 \sec (2 x) \tan (2 x)}{\sec (2 x) + 6 \tan (x)} + \frac{6}{\sec (2 x) + 6 \tan (x)} \sec^{2} (x)$

Step 6.4.2

Combine $\frac{6}{\sec (2 x) + 6 \tan (x)}$ and $\sec^{2} (x)$ .

$\frac{2 \sec (2 x) \tan (2 x)}{\sec (2 x) + 6 \tan (x)} + \frac{6 \sec^{2} (x)}{\sec (2 x) + 6 \tan (x)}$

Step 6.5

Combine the numerators over the common denominator.

$\frac{2 \sec (2 x) \tan (2 x) + 6 \sec^{2} (x)}{\sec (2 x) + 6 \tan (x)}$

Step 6.6

Factor $2$ out of $2 \sec (2 x) \tan (2 x) + 6 \sec^{2} (x)$ .

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Step 6.6.1

Factor $2$ out of $2 \sec (2 x) \tan (2 x)$ .

$\frac{2 (\sec (2 x) \tan (2 x)) + 6 \sec^{2} (x)}{\sec (2 x) + 6 \tan (x)}$

Step 6.6.2

Factor $2$ out of $6 \sec^{2} (x)$ .

$\frac{2 (\sec (2 x) \tan (2 x)) + 2 (3 \sec^{2} (x))}{\sec (2 x) + 6 \tan (x)}$

Step 6.6.3

Factor $2$ out of $2 (\sec (2 x) \tan (2 x)) + 2 (3 \sec^{2} (x))$ .

$\frac{2 (\sec (2 x) \tan (2 x) + 3 \sec^{2} (x))}{\sec (2 x) + 6 \tan (x)}$