Chapter 5: Problem 3
Evaluate the integrals in Exercises \(1-28\). $$\int_{-2}^{2} \frac{3}{(x+3)^{4}} d x$$
Short Answer
Expert verified
The integral evaluates to \(\frac{124}{125}\).
Step by step solution
01
Identify the Integral
We have to evaluate the integral \(\int_{-2}^{2} \frac{3}{(x+3)^{4}} dx\). This integral has limits from \(-2\) to \(2\) and the integrand \(\frac{3}{(x+3)^4}\) suggests a substitution can simplify this problem.
02
Choose a Substitution
To simplify the integral, use the substitution \( u = x + 3 \). This implies \( du = dx \) and as \( x \) varies from \(-2\) to \(2\), \( u \) will vary from \(1\) to \(5\).
03
Change the Limits of Integration
After substitution, change the limits of integration: when \( x = -2 \), \( u = 1 \), and when \( x = 2 \), \( u = 5 \). The integral converts to \(\int_{1}^{5} \frac{3}{u^4} du\).
04
Integrate the Simplified Function
The integral \(\int_{1}^{5} \frac{3}{u^4} du\) can be rewritten as \(3\int_{1}^{5} u^{-4} du\). The integral of \(u^{-4}\) is \(-\frac{1}{3} u^{-3} + C\).
05
Evaluate the Definite Integral
Now we evaluate the indefinite integral from \(1\) to \(5\):\[3\left[-\frac{1}{3} u^{-3}\right]_{1}^{5} = 3\left[-\frac{1}{3} \left(\frac{1}{125}\right) - \left(-\frac{1}{3} \right)\right]\]Simplifying gives:\[3\left(-\frac{1}{375} + \frac{1}{3}\right) = 3\left(\frac{125}{375} - \frac{1}{375}\right) = 3\times \frac{124}{375}\]Continuing with the arithmetic:\[= \frac{372}{375}, \text{ which simplifies to } \frac{124}{125}.\]
06
Conclude with Final Result
The evaluated definite integral is \(\frac{124}{125}\).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution in Integration
When solving an integral, substitution can be a powerful technique to simplify the problem. By changing the variable of integration, you can make the integral easier to evaluate.
In the exercise, the substitution chosen was: \( u = x + 3 \).
In the exercise, the substitution chosen was: \( u = x + 3 \).
- This change simplifies the expressions within the integral.
- Substitution modifies both the integrand and the limits of integration.
Limits of Integration
Adjusting the limits of integration is an essential part of substitution.
- After substituting \( u = x + 3 \), recalculate the limits based on this new variable.
- Initial limits of \( x = -2 \) to \( x = 2 \) change accordingly; converting to \( u = 1 \) to \( u = 5 \).
- The new limits must match the substitution equation.
- Always transform limits in line with the substitution used.
Definite Integral Evaluation
Definite integral evaluation finalizes the process, converting the antiderivative back into a number representing area under the curve.In this exercise, you started with \( 3\int_{1}^{5} u^{-4} du \), and then found its antiderivative:
- The antiderivative of \( u^{-4} \) is \( -\frac{1}{3} u^{-3} + C \).
- With this, you evaluate it between the new limits \( u = 1 \) and \( u = 5 \).
- First, plug in the upper limit into the antiderivative.
- Then, subtract the result of plugging in the lower limit.