Chapter 7: Problem 8
Calculate the following iterated integrals. $$ \int_{0}^{1}\left(\int_{0}^{x} e^{x+y} d y\right) d x $$
Short Answer
Expert verified
\( \frac{1}{2} e^2 - e + \frac{1}{2} \)
Step by step solution
01
Understand the Inner Integral
Identify the inner integral \(\int_{0}^{x} e^{x+y} dy\). Treat \(x\) as a constant while integrating with respect to \(y\).
02
Integrate the Inner Integral
Integrate \(e^{x+y}\) with respect to \( y \). Since \(x\) is constant, we have \(\int_{0}^{x} e^{x+y} dy = e^x \int_{0}^{x} e^{y} dy = e^x \big|_{0}^{x} e^y \).
03
Evaluate the Inner Integral
Evaluate the result of the inner integral: \(e^x \big|_{0}^{x} e^{y} = e^x (e^x - e^0) = e^x (e^x - 1)\). This simplifies to \(e^{2x} - e^x\).
04
Understand the Outer Integral
The outer integral now becomes \(\int_{0}^{1} (e^{2x} - e^x) dx \).
05
Integrate the Outer Integral
Integrate \(e^{2x} - e^x\) with respect to \(x\). This gives \(\int_{0}^{1} e^{2x} dx - \int_{0}^{1} e^x dx \).
06
Evaluate the Outer Integral
Evaluate \( \int_{0}^{1} e^{2x} dx \) and \( \int_{0}^{1} e^x dx \): \( \int_{0}^{1} e^{2x} dx = \frac{1}{2} e^{2x} \bigg|_{0}^{1} \) giving \( \frac{1}{2} (e^2 - 1) \), and \( \int_{0}^{1} e^x dx = e^x \bigg|_{0}^{1} = e - 1 \).
07
Combine and Simplify
Combine the results: \(\frac{1}{2} (e^2 - 1) - (e - 1) = \frac{1}{2}e^2 - \frac{1}{2} - e + 1 = \frac{1}{2} e^2 - e + \frac{1}{2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integration by Parts
Integration by parts is a powerful technique used in calculus to integrate products of functions. It's based on the product rule for differentiation. The formula for integration by parts is: \[ \int u \, dv = uv - \int v \, du\]\. To break this down:
- Choose parts of the integrand as \(u\) and \(dv\).
- Differentiate \(u\) to find \(du\).
- Integrate \(dv\) to find \(v\).
- Plug the parts into the formula.
- Simplify and integrate any remaining terms.
Definite Integrals
Definite integrals represent the area under a curve within a specified range. For an integral \[ \int_{a}^{b} f(x) \, dx \], \(a\) and \(b\) are the limits of integration. The process involves:
- Finding the antiderivative of \(f(x)\), denoted as \[ F(x) \].
- Evaluating \(F(x)\) at the upper limit \(b\) and the lower limit \(a\).
- Subtracting the value at \(a\) from the value at \(b\), written as \[F(b) - F(a). \]
Exponential Functions
Exponential functions have the form \[ e^x \]. They are unique in calculus due to their property: the derivative and the integral of \[ e^x \] are both \[ e^x \]. This characteristic simplifies many integration problems.
However, complications can arise when the exponent is more complex, such as \[ e^{2x} \]. In these cases:
However, complications can arise when the exponent is more complex, such as \[ e^{2x} \]. In these cases:
- Apply the chain rule for differentiation.
- Consider substitution methods for integration.