Chapter 6: Problem 30
Find the area enclosed by the given curves. $$ y=e^{2 x}, y=e^{-2 x}, x=-1, x=2 $$
Short Answer
Expert verified
The area enclosed by the curves is \( \frac{1}{2} (e^{4} + e^{-4} - e^{2} - e^{-2}) \).
Step by step solution
01
Understand the Problem
We need to find the area enclosed between the two curves given by the equations \( y = e^{2x} \) and \( y = e^{-2x} \), within the vertical boundaries defined by \( x = -1 \) and \( x = 2 \).
02
Identify the Intersection Points
The curves intersect when \( e^{2x} = e^{-2x} \). Solving this equation, we get \( e^{4x} = 1 \), which implies \( 4x = 0 \), hence \( x = 0 \). Thus, the curves intersect at \( x = 0 \).
03
Set Up the Integral
We will compute the area between the curves by integrating from \( x = -1 \) to \( x = 2 \). The area \( A \) is given by the integral of the difference of the two functions: \[A = \int_{-1}^{2} \left(e^{2x} - e^{-2x}\right) \, dx\]
04
Integrate the Functions
Calculate the integral \[\int \left(e^{2x} - e^{-2x}\right) \, dx = \int e^{2x} \, dx - \int e^{-2x} \, dx\].For \( \int e^{2x} \, dx \), use substitution with \( u = 2x \) to find the antiderivative: \( \frac{1}{2}e^{2x} \).For \( \int e^{-2x} \, dx \), use substitution with \( v = -2x \) to find the antiderivative: \(-\frac{1}{2}e^{-2x}\).
05
Evaluate the Integral
Using the antiderivatives, the definite integral is:\[\left[ \frac{1}{2}e^{2x} + \frac{1}{2}e^{-2x} \right]_{x=-1}^{x=2} = \left( \frac{1}{2}e^{4} + \frac{1}{2}e^{-4} \right) - \left( \frac{1}{2}e^{-2} + \frac{1}{2}e^{2} \right)\].
06
Simplify the Expression
Compute the values:\( e^{4}, e^{-4}, e^{2}, e^{-2} \). Substituting these, we simplify to:\[\frac{1}{2}(e^{4} + e^{-4} - e^{-2} - e^{2})\],which can be simplified further for numeric approximation.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integration
Integration is a fundamental concept in calculus used to calculate areas under curves. It involves adding up infinitesimally small areas to find a total area.
In mathematical terms, integration is the process of finding the integral of a function. The integral represents the accumulation of quantities, such as area, volume, or other central concepts.
When performing integration, there are a few key elements to consider:
In mathematical terms, integration is the process of finding the integral of a function. The integral represents the accumulation of quantities, such as area, volume, or other central concepts.
When performing integration, there are a few key elements to consider:
- The integrand: The function you are integrating, often noted as \( f(x) \).
- The limits of integration: These define the range over which you are integrating, expressed as \( a \) to \( b \).
- The differential: Indicated by \( dx \), shows the variable with respect to which integration is performed.
Area Between Curves
The area between curves is a common problem in calculus where we determine the region between two graphs. Specifically, if two functions \( f(x) \) and \( g(x) \) are graphed on a coordinate plane, the goal is to find the area contained between them.
To compute this area, we integrate their difference over a specific interval. Essentially:
To compute this area, we integrate their difference over a specific interval. Essentially:
- Identify the functions and their respective intersection points.
- Determine which curve is on top; let’s say \( f(x) \) is above \( g(x) \).
- Set up the integral of the difference \( f(x) - g(x) \) from one intersection point to another.
Exponential Functions
Exponential functions are a type of mathematical function in which an independent variable, \( x \), appears in the exponent. These functions are expressed in the form \( y = a^x \) where \( a \) is a constant, often the natural base \( e \), and \( x \) is the variable.
Exponential functions have several key properties:
Exponential functions have several key properties:
- They change rapidly and can model growth or decay processes, such as population dynamics or radioactive decay.
- Their graphs are curved, often rising or falling steeply.
- They are defined for all real numbers \( x \).