Chapter 5: Problem 37
Use a definite integral to find the area under each curve between the given \(x\) -values. For Exercises \(19-24\), also make a sketch of the curve showing the region. \(f(x)=2 e^{x}\) from \(x=0\) to \(x=\ln 3\)
Short Answer
Expert verified
The area is 4.
Step by step solution
01
Understand the problem
We need to find the area under the curve of the function \( f(x) = 2e^x \) between \( x = 0 \) and \( x = \ln 3 \). We will use a definite integral to find this area.
02
Set up the definite integral
We set up the integral for the function \( f(x) = 2e^x \) from \( x = 0 \) to \( x = \ln 3 \): \[ \int_{0}^{\ln 3} 2e^x \, dx \]
03
Integrate the function
To integrate \( 2e^x \), recall that the integral of \( e^x \) with respect to \( x \) is \( e^x \). Therefore, the integral of \( 2e^x \) is:\[ \int 2e^x \, dx = 2e^x + C \] where \( C \) is the constant of integration, which we do not need for definite integrals.
04
Evaluate the definite integral
Now substitute the limits \( x = \ln 3 \) and \( x = 0 \) into the integrated function: \[2e^{\ln 3} - 2e^0 = 2 \times 3 - 2 \times 1 = 6 - 2 = 4\]
05
Sketch the curve and the region
The curve of \( f(x) = 2e^x \) is an exponential curve that starts at (0,2) when \( x = 0 \). At \( x = \ln 3 \), the function value is 6, so the curve passes through (\( \ln 3 \), 6). The region under the curve from \( x = 0 \) to \( x = \ln 3 \) forms a bounded area which is computed to be 4. Sketch this curve and shade the region between these x-values.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Area Under Curve
Understanding the area under a curve is a key part of integral calculus. When you're working with a function like \( f(x) = 2e^x \), finding the area under its curve on a specific interval tells you about the accumulation of values over that range.
This can be interpreted in many real-world applications, such as calculating total revenue over time or finding the distance traveled. To find this area, we use a definite integral, which involves calculating the integral of the function across a certain interval of \(x\).
This can be interpreted in many real-world applications, such as calculating total revenue over time or finding the distance traveled. To find this area, we use a definite integral, which involves calculating the integral of the function across a certain interval of \(x\).
- First, you label the function and the interval. For our exercise, the interval is from \(x = 0\) to \(x = \ln 3\).
- Next, set up the definite integral, \( \int_{0}^{\ln 3} 2e^x \, dx \), to represent the area you want to find.
- Finally, solve this integral and evaluate it using the limits provided. This process gives the area under the curve between the specified \(x\)-values, which in this case is 4 square units.
Exponential Functions
Exponential functions, such as \( f(x) = e^x \), grow at an increasing rate and are shown as curved lines on a graph. In our exercise, we have an exponential function with a multiplier, \( 2e^x \).
This multiplier stretches the graph vertically, making it rise more sharply as \( x \) increases.
This multiplier stretches the graph vertically, making it rise more sharply as \( x \) increases.
- For \( 2e^x \), at \( x = 0 \), the value begins at 2, since anything raised to the power of 0 is 1, making it \(2 \times 1 = 2\).
- Exponential functions are powerful in modeling growth processes, including populations, radioactive decay, and compound interest due to their rapid increase.
- Graphically, this curve is smooth, continuous, and increases without bounds as \( x \) grows larger.
Integral Calculus
Integral calculus is a branch of mathematics focused on the concept of accumulation. It often helps in finding areas, volumes, and other quantities under curves. In particular, definite integrals provide a precise method to calculate these quantities for bounded curves.
With our exercise, integral calculus allows us to find the total area under \( f(x) = 2e^x \) from \( x = 0 \) to \( x = \ln 3 \).
With our exercise, integral calculus allows us to find the total area under \( f(x) = 2e^x \) from \( x = 0 \) to \( x = \ln 3 \).
- The definite integral \( \int_{a}^{b} f(x) \, dx \) represents the accumulated area from \( x = a \) to \( x = b \), using the integrated function value.
- The definite integral has two parts: finding the anti-derivative and applying the limits to this anti-derivative function.
- In practical terms, it translates the concept of a curve's area into precise numerical values, offering solutions to real-world problems involving density, force, and other accumulated quantities.