Calculus Examples

$lim_{x \to \frac{π}{2}} {(1 + \sec (3 x))}^{\cot (3 x)}$

Step 1

Use the properties of logarithms to simplify the limit.

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Step 1.1

Rewrite ${(1 + \sec (3 x))}^{\cot (3 x)}$ as $e^{\ln ({(1 + \sec (3 x))}^{\cot (3 x)})}$ .

$lim_{x \to \frac{π}{2}} e^{\ln ({(1 + \sec (3 x))}^{\cot (3 x)})}$

Step 1.2

Expand $\ln ({(1 + \sec (3 x))}^{\cot (3 x)})$ by moving $\cot (3 x)$ outside the logarithm.

$lim_{x \to \frac{π}{2}} e^{\cot (3 x) \ln (1 + \sec (3 x))}$

Step 2

Set up the limit as a left-sided limit.

$lim_{x \to {(\frac{π}{2})}^{-}} e^{\cot (3 x) \ln (1 + \sec (3 x))}$

Step 3

Evaluate the limits by plugging in the value for the variable.

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Step 3.1

Evaluate the limit of $e^{\cot (3 x) \ln (1 + \sec (3 x))}$ by plugging in $\frac{π}{2}$ for $x$ .

$e^{\cot (3 \frac{π}{2}) \ln (1 + \sec (3 \frac{π}{2}))}$

Step 3.2

Rewrite $\sec (3 \frac{π}{2})$ in terms of sines and cosines.

$e^{\cot (3 \frac{π}{2}) \ln (1 + \frac{1}{\cos (3 \frac{π}{2})})}$

Step 3.3

Combine $3$ and $\frac{π}{2}$ .

$e^{\cot (3 \frac{π}{2}) \ln (1 + \frac{1}{\cos (\frac{3 π}{2})})}$

Step 3.4

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.

$e^{\cot (3 \frac{π}{2}) \ln (1 + \frac{1}{\cos (\frac{π}{2})})}$

Step 3.5

The exact value of $\cos (\frac{π}{2})$ is $0$ .

$e^{\cot (3 \frac{π}{2}) \ln (1 + \frac{1}{0})}$

Step 3.6

Since $e^{\cot (3 \frac{π}{2}) \ln (1 + \frac{1}{0})}$ is undefined, the limit does not exist.

$Does not exist$

Step 4

Set up the limit as a right-sided limit.

$lim_{x \to {(\frac{π}{2})}^{+}} e^{\cot (3 x) \ln (1 + \sec (3 x))}$

Step 5

Evaluate the right-sided limit.

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Step 5.1

Move the limit into the exponent.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \cot (3 x) \ln (1 + \sec (3 x))}$

Step 5.2

Rewrite $\cot (3 x) \ln (1 + \sec (3 x))$ as $\frac{\ln (1 + \sec (3 x))}{\frac{1}{\cot (3 x)}}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\ln (1 + \sec (3 x))}{\frac{1}{\cot (3 x)}}}$

Step 5.3

Apply L'Hospital's rule.

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Step 5.3.1

Evaluate the limit of the numerator and the limit of the denominator.

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Step 5.3.1.1

Take the limit of the numerator and the limit of the denominator.

$e^{\frac{lim_{x \to {(\frac{π}{2})}^{+}} \ln (1 + \sec (3 x))}{lim_{x \to {(\frac{π}{2})}^{+}} \frac{1}{\cot (3 x)}}}$

Step 5.3.1.2

As log approaches infinity, the value goes to $\infty$ .

$e^{\frac{\infty}{lim_{x \to {(\frac{π}{2})}^{+}} \frac{1}{\cot (3 x)}}}$

Step 5.3.1.3

Evaluate the limit of the denominator.

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Step 5.3.1.3.1

Apply trigonometric identities.

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Step 5.3.1.3.1.1

Rewrite $\cot (3 x)$ in terms of sines and cosines.

$e^{\frac{\infty}{lim_{x \to {(\frac{π}{2})}^{+}} \frac{1}{\frac{\cos (3 x)}{\sin (3 x)}}}}$

Step 5.3.1.3.1.2

Multiply by the reciprocal of the fraction to divide by $\frac{\cos (3 x)}{\sin (3 x)}$ .

$e^{\frac{\infty}{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\sin (3 x)}{\cos (3 x)}}}$

Step 5.3.1.3.1.3

Convert from $\frac{\sin (3 x)}{\cos (3 x)}$ to $\tan (3 x)$ .

$e^{\frac{\infty}{lim_{x \to {(\frac{π}{2})}^{+}} \tan (3 x)}}$

Step 5.3.1.3.2

As the $x$ values approach $\frac{π}{2}$ from the right, the function values decrease without bound.

$e^{\frac{\infty}{- \infty}}$

Step 5.3.1.3.3

Infinity divided by infinity is undefined.

Undefined

$e^{\frac{\infty}{- \infty}}$

Step 5.3.1.4

Infinity divided by infinity is undefined.

Undefined

$e^{\frac{\infty}{- \infty}}$

Step 5.3.2

Since $\frac{\infty}{- \infty}$ is of indeterminate form, apply L'Hospital's Rule. L'Hospital's Rule states that the limit of a quotient of functions is equal to the limit of the quotient of their derivatives.

$lim_{x \to {(\frac{π}{2})}^{+}} \frac{\ln (1 + \sec (3 x))}{\frac{1}{\cot (3 x)}} = lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{d}{d x} [\ln (1 + \sec (3 x))]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}$

Step 5.3.3

Find the derivative of the numerator and denominator.

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Step 5.3.3.1

Differentiate the numerator and denominator.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{d}{d x} [\ln (1 + \sec (3 x))]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.2

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 $g (x) = 1 + \sec (3 x)$ .

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Step 5.3.3.2.1

To apply the Chain Rule, set $u_{1}$ as $1 + \sec (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{d}{d u_{1}} [\ln (u_{1})] \frac{d}{d x} [1 + \sec (3 x)]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.2.2

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{u_{1}} \frac{d}{d x} [1 + \sec (3 x)]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.2.3

Replace all occurrences of $u_{1}$ with $1 + \sec (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{1 + \sec (3 x)} \frac{d}{d x} [1 + \sec (3 x)]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.3

By the Sum Rule, the derivative of $1 + \sec (3 x)$ with respect to $x$ is $\frac{d}{d x} [1] + \frac{d}{d x} [\sec (3 x)]$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{1 + \sec (3 x)} (\frac{d}{d x} [1] + \frac{d}{d x} [\sec (3 x)])}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.4

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{1 + \sec (3 x)} (0 + \frac{d}{d x} [\sec (3 x)])}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.5

Add $0$ and $\frac{d}{d x} [\sec (3 x)]$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{1 + \sec (3 x)} \frac{d}{d x} [\sec (3 x)]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.6

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 $g (x) = 3 x$ .

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Step 5.3.3.6.1

To apply the Chain Rule, set $u_{2}$ as $3 x$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{1 + \sec (3 x)} \frac{d}{d u_{2}} [\sec (u_{2})] \frac{d}{d x} [3 x]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.6.2

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{1 + \sec (3 x)} \sec (u_{2}) \tan (u_{2}) \frac{d}{d x} [3 x]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.6.3

Replace all occurrences of $u_{2}$ with $3 x$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{1}{1 + \sec (3 x)} \sec (3 x) \tan (3 x) \frac{d}{d x} [3 x]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.7

Combine $\sec (3 x)$ and $\frac{1}{1 + \sec (3 x)}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\sec (3 x)}{1 + \sec (3 x)} \tan (3 x) \frac{d}{d x} [3 x]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.8

Combine $\tan (3 x)$ and $\frac{\sec (3 x)}{1 + \sec (3 x)}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\tan (3 x) \sec (3 x)}{1 + \sec (3 x)} \frac{d}{d x} [3 x]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.9

Since $3$ is constant with respect to $x$ , the derivative of $3 x$ with respect to $x$ is $3 \frac{d}{d x} [x]$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\tan (3 x) \sec (3 x)}{1 + \sec (3 x)} \cdot 3 \frac{d}{d x} [x]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.10

Combine $3$ and $\frac{\tan (3 x) \sec (3 x)}{1 + \sec (3 x)}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \tan (3 x) \sec (3 x)}{1 + \sec (3 x)} \frac{d}{d x} [x]}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.11

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \tan (3 x) \sec (3 x)}{1 + \sec (3 x)} \cdot 1}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.12

Multiply $\frac{3 \tan (3 x) \sec (3 x)}{1 + \sec (3 x)}$ by $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \tan (3 x) \sec (3 x)}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13

Simplify.

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Step 5.3.3.13.1

Simplify the numerator.

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Step 5.3.3.13.1.1

Rewrite $\tan (3 x)$ in terms of sines and cosines.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \frac{\sin (3 x)}{\cos (3 x)} \sec (3 x)}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.1.2

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\frac{3 \sin (3 x)}{\cos (3 x)} \sec (3 x)}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.1.3

Rewrite $\sec (3 x)$ in terms of sines and cosines.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\frac{3 \sin (3 x)}{\cos (3 x)} \cdot \frac{1}{\cos (3 x)}}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.1.4

Multiply $\frac{3 \sin (3 x)}{\cos (3 x)} \cdot \frac{1}{\cos (3 x)}$ .

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Step 5.3.3.13.1.4.1

Multiply $\frac{3 \sin (3 x)}{\cos (3 x)}$ by $\frac{1}{\cos (3 x)}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\frac{3 \sin (3 x)}{\cos (3 x) \cos (3 x)}}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.1.4.2

Raise $\cos (3 x)$ to the power of $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\frac{3 \sin (3 x)}{\cos^{1} (3 x) \cos (3 x)}}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.1.4.3

Raise $\cos (3 x)$ to the power of $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\frac{3 \sin (3 x)}{\cos^{1} (3 x) \cos^{1} (3 x)}}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.1.4.4

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\frac{3 \sin (3 x)}{{\cos (3 x)}^{1 + 1}}}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.1.4.5

Add $1$ and $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x)}}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.2

Combine terms.

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Step 5.3.3.13.2.1

Rewrite $\frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x)}}{1 + \sec (3 x)}$ as a product.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x)} \cdot \frac{1}{1 + \sec (3 x)}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.13.2.2

Multiply $\frac{3 \sin (3 x)}{\cos^{2} (3 x)}$ by $\frac{1}{1 + \sec (3 x)}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{d}{d x} [\frac{1}{\cot (3 x)}]}}$

Step 5.3.3.14

Rewrite $\cot (3 x)$ in terms of sines and cosines.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{d}{d x} [\frac{1}{\frac{\cos (3 x)}{\sin (3 x)}}]}}$

Step 5.3.3.15

Multiply by the reciprocal of the fraction to divide by $\frac{\cos (3 x)}{\sin (3 x)}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{d}{d x} [1 \frac{\sin (3 x)}{\cos (3 x)}]}}$

Step 5.3.3.16

Write $1$ as a fraction with denominator $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{d}{d x} [\frac{1}{1} \cdot \frac{\sin (3 x)}{\cos (3 x)}]}}$

Step 5.3.3.17

Simplify.

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Step 5.3.3.17.1

Rewrite the expression.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{d}{d x} [1 \frac{\sin (3 x)}{\cos (3 x)}]}}$

Step 5.3.3.17.2

Multiply $\frac{\sin (3 x)}{\cos (3 x)}$ by $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{d}{d x} [\frac{\sin (3 x)}{\cos (3 x)}]}}$

Step 5.3.3.18

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 $f (x) = \sin (3 x)$ and $g (x) = \cos (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos (3 x) \frac{d}{d x} [\sin (3 x)] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.19

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \sin (x)$ and $g (x) = 3 x$ .

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Step 5.3.3.19.1

To apply the Chain Rule, set $u_{1}$ as $3 x$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos (3 x) \frac{d}{d u_{1}} [\sin (u_{1})] \frac{d}{d x} [3 x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.19.2

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos (3 x) \cos (u_{1}) \frac{d}{d x} [3 x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.19.3

Replace all occurrences of $u_{1}$ with $3 x$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos (3 x) \cos (3 x) \frac{d}{d x} [3 x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.20

Raise $\cos (3 x)$ to the power of $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos^{1} (3 x) \cos (3 x) \frac{d}{d x} [3 x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.21

Raise $\cos (3 x)$ to the power of $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos^{1} (3 x) \cos^{1} (3 x) \frac{d}{d x} [3 x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.22

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{{\cos (3 x)}^{1 + 1} \frac{d}{d x} [3 x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.23

Add $1$ and $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos^{2} (3 x) \frac{d}{d x} [3 x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.24

Since $3$ is constant with respect to $x$ , the derivative of $3 x$ with respect to $x$ is $3 \frac{d}{d x} [x]$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos^{2} (3 x) \cdot 3 \frac{d}{d x} [x] - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.25

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos^{2} (3 x) \cdot 3 \cdot 1 - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.26

Multiply $3$ by $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{\cos^{2} (3 x) \cdot 3 - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.27

Move $3$ to the left of $\cos^{2} (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cdot \cos^{2} (3 x) - \sin (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}}}$

Step 5.3.3.28

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \cos (x)$ and $g (x) = 3 x$ .

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Step 5.3.3.28.1

To apply the Chain Rule, set $u_{2}$ as $3 x$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) - \sin (3 x) \frac{d}{d u_{2}} [\cos (u_{2})] \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.28.2

The derivative of $\cos (u_{2})$ with respect to $u_{2}$ is $- \sin (u_{2})$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) - \sin (3 x) \cdot - 1 \sin (u_{2}) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.28.3

Replace all occurrences of $u_{2}$ with $3 x$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) - \sin (3 x) \cdot - 1 \sin (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.29

Multiply $- 1$ by $- 1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + 1 \sin (3 x) \sin (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.30

Multiply $\sin (3 x)$ by $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + \sin (3 x) \sin (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.31

Raise $\sin (3 x)$ to the power of $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + \sin^{1} (3 x) \sin (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.32

Raise $\sin (3 x)$ to the power of $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + \sin^{1} (3 x) \sin^{1} (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.33

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + {\sin (3 x)}^{1 + 1} \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.34

Add $1$ and $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + \sin^{2} (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.35

Since $3$ is constant with respect to $x$ , the derivative of $3 x$ with respect to $x$ is $3 \frac{d}{d x} [x]$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + \sin^{2} (3 x) \cdot 3 \frac{d}{d x} [x]}{\cos^{2} (3 x)}}}$

Step 5.3.3.36

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

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + \sin^{2} (3 x) \cdot 3 \cdot 1}{\cos^{2} (3 x)}}}$

Step 5.3.3.37

Multiply $3$ by $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + \sin^{2} (3 x) \cdot 3}{\cos^{2} (3 x)}}}$

Step 5.3.3.38

Move $3$ to the left of $\sin^{2} (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cos^{2} (3 x) + 3 \cdot \sin^{2} (3 x)}{\cos^{2} (3 x)}}}$

Step 5.3.3.39

Simplify the numerator.

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Step 5.3.3.39.1

Factor $3$ out of $3 \cos^{2} (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 (\cos^{2} (3 x)) + 3 \sin^{2} (3 x)}{\cos^{2} (3 x)}}}$

Step 5.3.3.39.2

Factor $3$ out of $3 \sin^{2} (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 (\cos^{2} (3 x)) + 3 (\sin^{2} (3 x))}{\cos^{2} (3 x)}}}$

Step 5.3.3.39.3

Factor $3$ out of $3 (\cos^{2} (3 x)) + 3 (\sin^{2} (3 x))$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 (\cos^{2} (3 x) + \sin^{2} (3 x))}{\cos^{2} (3 x)}}}$

Step 5.3.3.39.4

Rearrange terms.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 (\sin^{2} (3 x) + \cos^{2} (3 x))}{\cos^{2} (3 x)}}}$

Step 5.3.3.39.5

Apply pythagorean identity.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3 \cdot 1}{\cos^{2} (3 x)}}}$

Step 5.3.3.39.6

Multiply $3$ by $1$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}{\frac{3}{\cos^{2} (3 x)}}}$

Step 5.3.4

Multiply the numerator by the reciprocal of the denominator.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))} \cdot \frac{\cos^{2} (3 x)}{3}}$

Step 5.3.5

Multiply $\frac{3 \sin (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}$ by $\frac{\cos^{2} (3 x)}{3}$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{3 \sin (3 x) \cos^{2} (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x)) \cdot 3}}$

Step 5.3.6

Reduce.

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Step 5.3.6.1

Cancel the common factor of $3$ .

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Step 5.3.6.1.1

Cancel the common factor.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{3 \sin (3 x) \cos^{2} (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x)) \cdot 3}}$

Step 5.3.6.1.2

Rewrite the expression.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\sin (3 x) \cos^{2} (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}$

Step 5.3.6.2

Cancel the common factor of $\cos^{2} (3 x)$ .

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Step 5.3.6.2.1

Cancel the common factor.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\sin (3 x) \cos^{2} (3 x)}{\cos^{2} (3 x) (1 + \sec (3 x))}}$

Step 5.3.6.2.2

Rewrite the expression.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\sin (3 x)}{1 + \sec (3 x)}}$

Step 5.3.7

Rewrite $\sec (3 x)$ in terms of sines and cosines.

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\sin (3 x)}{1 + \frac{1}{\cos (3 x)}}}$

Step 5.3.8

Convert from $\frac{1}{\cos (3 x)}$ to $\sec (3 x)$ .

$e^{lim_{x \to {(\frac{π}{2})}^{+}} \frac{\sin (3 x)}{1 + \sec (3 x)}}$

Step 5.4

Since its numerator approaches a real number while its denominator is unbounded, the fraction $\frac{\sin (3 x)}{1 + \sec (3 x)}$ approaches $0$ .

$e^{0}$

Step 5.5

Anything raised to $0$ is $1$ .

$1$

Step 6

If either of the one-sided limits does not exist, the limit does not exist.

$Does not exist$