Textbook Question
23-64. Integration Evaluate the following integrals.
35. ∫ (x² + 12x - 4)/(x³ - 4x) dx
Ch. 8 - Integration Techniques
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243
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Table of contents
- Ch. 1 - Functions210
- Ch. 2 - Limits371
- Ch. 3 - Derivatives633
- Ch. 4 - Applications of the Derivative412
- Ch. 5 - Integration328
- Ch. 6 - Applications of Integration331
- Ch. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions177
- Ch. 8 - Integration Techniques394
- Ch. 9 - Differential Equations179
- Ch. 10 - Sequences and Infinite Series339
- Ch. 11 - Power Series218
- Ch.12 - Parametric and Polar Curves215
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 8, Problem 8.8.54
54–57. {Use of Tech} Comparing the Midpoint and Trapezoid Rules Compare the errors in the Midpoint and Trapezoid Rules with n = 4, 8, 16, and 32 subintervals when they are applied to the following integrals (with their exact values given).
54. ∫(from 0 to π/2) sin⁶x dx = 5π/32
Verified step by step guidance1
Identify the integral to approximate: \(\int_0^{\frac{\pi}{2}} \sin^6 x \, dx\) with exact value \(\frac{5\pi}{32}\).
Recall the formulas for the Midpoint Rule and the Trapezoid Rule for approximating integrals with \(n\) subintervals:
- Midpoint Rule: \(M_n = \Delta x \sum_{i=1}^n f\left(x_{i-\frac{1}{2}}\right)\),
- Trapezoid Rule: \(T_n = \frac{\Delta x}{2} \left(f(x_0) + 2 \sum_{i=1}^{n-1} f(x_i) + f(x_n)\right)\),
where \(\Delta x = \frac{b - a}{n}\) and \(x_i = a + i \Delta x\).
For each \(n = 4, 8, 16, 32\), calculate \(\Delta x = \frac{\pi/2 - 0}{n} = \frac{\pi}{2n}\) and determine the sample points:
- For Midpoint Rule, use midpoints \(x_{i-\frac{1}{2}} = a + \left(i - \frac{1}{2}\right) \Delta x\),
- For Trapezoid Rule, use endpoints \(x_i = a + i \Delta x\) for \(i = 0, 1, ..., n\).
Evaluate \(f(x) = \sin^6 x\) at the required points for each rule and sum according to the formulas to get approximations \(M_n\) and \(T_n\).
Calculate the absolute errors for each \(n\) and each rule by subtracting the approximate values from the exact value \(\frac{5\pi}{32}\):
\(\text{Error}_{Midpoint} = \left| M_n - \frac{5\pi}{32} \right|\),
\(\text{Error}_{Trapezoid} = \left| T_n - \frac{5\pi}{32} \right|\).
Compare these errors to analyze which rule gives better accuracy as \(n\) increases.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Numerical Integration Methods
Numerical integration approximates definite integrals when exact solutions are difficult. The Midpoint Rule estimates the integral using function values at subinterval midpoints, while the Trapezoid Rule uses linear approximations between endpoints. Both methods divide the interval into subintervals to improve accuracy.
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Error Analysis in Numerical Integration
Error analysis evaluates how close a numerical approximation is to the exact integral. The Midpoint Rule error depends on the second derivative of the function and generally decreases faster than the Trapezoid Rule error, which also depends on the second derivative but with a different constant. Understanding error behavior helps compare method efficiency.
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04:57Determining Error and Relative Error
Effect of Subinterval Number (n) on Accuracy
Increasing the number of subintervals (n) in numerical methods typically reduces approximation error. Both Midpoint and Trapezoid Rules improve as n grows, but their error rates differ. Analyzing errors for n = 4, 8, 16, and 32 shows how refinement impacts accuracy and convergence speed.
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Related Practice
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Textbook Question
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