Chapter 7: Problem 20
Find the integral. $$ \int(\sin x)^{e} \cos x d x $$
Short Answer
Expert verified
\( \int (\sin x)^{e} \cos x \, dx = \frac{(\sin x)^{e+1}}{e+1} + C \).
Step by step solution
01
Identify the Integral Structure
The integral is of the form \( \int u^n \, du\), where \( u = \sin x \) and \( n = e \). We need to find the derivative \( du \) in terms of \( dx \), which is \( du = \cos x \, dx \). This simplifies our integral.
02
Apply Substitution
Let's substitute \( u = \sin x \). Then \( du = \cos x \, dx \). Therefore, the integral becomes \( \int u^e \, du \). This is a standard power rule integral.
03
Integrate using the Power Rule
Using the power rule for integration \( \int u^n \, du = \frac{u^{n+1}}{n+1} + C \), where \( n eq -1 \), we find the integral \( \int u^e \, du \) to be \( \frac{u^{e+1}}{e+1} + C \).
04
Back-substitute \( u \)
Replace \( u \) with \( \sin x \) in the result. Thus, the integral becomes \( \frac{(\sin x)^{e+1}}{e+1} + C \).
05
Final Review and Simplify
Ensure the final expression is simplified correctly and matches the problem's requirements. The final result is \( \frac{(\sin x)^{e+1}}{e+1} + C \), where \( C \) is the constant of integration.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution Method in Integration
The substitution method is a powerful technique used in integration, particularly useful for simplifying integrals by making a substitution. In our problem, it helps us transform a complex integral into a simpler one. The essence of this method is to identify a part of the integral which when substituted, reduces the complexity of the expression.
Here's how it works:
Here's how it works:
- Identify a substitution that simplifies the integrand. In our example, the substitution was letting \( u = \sin x \), which made the integral easier to handle.
- Calculate \( du \), the differential of your substitution variable. For \( u = \sin x \), we found \( du = \cos x \, dx \).
- Re-write the entire integral in terms of \( u \). This transformed our original integral \( \int (\sin x)^{e} \cos x \, dx \) into a simpler form \( \int u^{e} \, du \).
Power Rule in Integration
The power rule for integration is a basic, yet essential tool. It applies to integrals of the form \( \int u^n \, du \), where \( n \) is a real number.
Here's the formula:
\[ \int u^e \, du = \frac{u^{e+1}}{e+1} + C \]This step is simple yet critical, ensuring we handle powers correctly when integrating functions. The power rule turns a daunting task into a straightforward arithmetic operation.
Here's the formula:
- If \( n eq -1 \), then \( \int u^n \, du = \frac{u^{n+1}}{n+1} + C \).
- \( C \) represents the constant of integration, crucial for accounting for all possible indefinite integrals.
\[ \int u^e \, du = \frac{u^{e+1}}{e+1} + C \]This step is simple yet critical, ensuring we handle powers correctly when integrating functions. The power rule turns a daunting task into a straightforward arithmetic operation.
Definite and Indefinite Integrals
Integrals are categorized into two types: definite and indefinite.
Indefinite Integrals
Indefinite Integrals
- These yield a family of functions, given by \( f(x) + C \), where \( C \) is the integration constant.
- Indefinite integrals do not have set bounds; they describe general antiderivatives.
- Our problem focuses on finding an indefinite integral, illustrated by the final result \( \frac{(\sin x)^{e+1}}{e+1} + C \).
- These calculate the area under a curve between two points, providing a specific numerical result.
- Definite integrals have limits and do not include a constant of integration.
- While our exercise doesn't include one, understanding the difference is crucial for applying integration properly.