Chapter 5: Problem 32
Find the general antiderivative of the given function. $$ f(x)=\sec ^{2}(4 x) $$
Short Answer
Expert verified
The general antiderivative of \( f(x) = \sec^2(4x) \) is \( \frac{1}{4} \tan(4x) + C \).
Step by step solution
01
Recognize the Function
The function we need to find the general antiderivative for is \( f(x) = \sec^2(4x) \). We recognize that this is similar to the derivative of the tangent function, since \( \frac{d}{dx}[\tan(x)] = \sec^2(x) \).
02
Consider U-substitution
Because the function involves \( 4x \) instead of just \( x \), we will use a substitution method. Let \( u = 4x \), which implies \( du = 4 \, dx \). Then, \( dx = \frac{1}{4} \, du \).
03
Rewrite the Integral
Rewrite the integral in terms of \( u \) as follows: \( \int \sec^2(4x) \, dx = \int \sec^2(u) \cdot \frac{1}{4} \, du \). This simplifies to \( \frac{1}{4} \int \sec^2(u) \, du \).
04
Find the Antiderivative
The antiderivative of \( \sec^2(u) \) is \( \tan(u) + C \), where \( C \) is the constant of integration. Thus, \( \int \sec^2(u) \ du = \tan(u) + C \).
05
Substitute back to x
Substitute \( u = 4x \) back into the antiderivative expression: \( \frac{1}{4} \int \sec^2(u) \, du = \frac{1}{4}(\tan(u) + C) = \frac{1}{4}(\tan(4x) + C) \).
06
Write Final Expression
Distribute the \( \frac{1}{4} \) to obtain the final expression for the general antiderivative: \( \frac{1}{4} \tan(4x) + C \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
U-substitution
U-substitution is a powerful technique used in calculus to simplify the process of integration. It involves changing the variables of integration from one set to another, which makes a complex integral easier to evaluate. In our specific example, we needed to find the antiderivative of the function \( f(x) = \sec^2(4x) \). This function involves the composite argument \( 4x \), instead of just \( x \), which hints that u-substitution may be a handy approach.
Here's how it works:
Here's how it works:
- Identify the inner function: In the expression \( \sec^2(4x) \), the inner function is \( 4x \).
- Choose a substitution: Set \( u = 4x \) so that \( du = 4 \, dx \), which leads to \( dx = \frac{1}{4} \, du \).
- Rewrite the integral: By substituting these into the integral, we transform it into a simpler form.
Integration
Integration is the process of finding an antiderivative or integral, which is essentially the opposite operation of differentiation. In the context of our function \( f(x) = \sec^2(4x) \), integration aims to find a function whose derivative is \( \sec^2(4x) \).
After substitution, we get an integral in terms of \( u \):
After substitution, we get an integral in terms of \( u \):
- \( \int \sec^2(u) \cdot \frac{1}{4} \, du \) simplifies to \( \frac{1}{4} \int \sec^2(u) \, du \).
- This transforms a more complicated integral into something straightforward: \( \sec^2(u) \).
Trigonometric Functions
Trigonometric functions play a crucial role in calculus, especially when working with problems involving integrals and derivatives. In this case, understanding the derivative relationships of trigonometric functions is essential.
For example:
For example:
- The derivative of \( \tan(x) \) is \( \sec^2(x) \), which means while integrating \( \sec^2(x) \), we revert to the function whose derivative it represents, \( \tan(x) \).
- Recognizing such relationships is key when performing tasks like finding antiderivatives and solving integrals.