Table of contents

0. Functions7h 52m
1. Limits and Continuity2h 2m
2. Intro to Derivatives1h 33m
3. Techniques of Differentiation3h 18m
4. Applications of Derivatives2h 38m
5. Graphical Applications of Derivatives6h 2m
6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
7. Antiderivatives & Indefinite Integrals1h 26m
8. Definite Integrals4h 44m
9. Graphical Applications of Integrals2h 27m
- Area Between Curves
  1h 18m
- Introduction to Volume & Disk Method
  1h 8m
10. Physics Applications of Integrals 3h 16m
- Kinematics
  1h 13m
- Work
  2h 3m
11. Integrals of Inverse, Exponential, & Logarithmic Functions2h 34m
12. Techniques of Integration7h 39m
13. Intro to Differential Equations2h 55m
14. Sequences & Series5h 36m
15. Power Series2h 19m
- Introduction to Power Series
  1h 9m
- Taylor Series & Taylor Polynomials
  1h 10m
16. Parametric Equations & Polar Coordinates7h 58m

8. Definite Integrals

Introduction to Definite Integrals

Calculus

8. Definite Integrals

Introduction to Definite Integrals

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3:30 minutes

Problem 5.R.86

Textbook Question

Evaluating integrals Evaluate the following integrals.

∫₀⁵ |2𝓍―8|d𝓍

Verified step by step guidance

Step 1: Recognize that the integral involves the absolute value function |2𝓍 - 8|. Absolute value functions can be split into piecewise functions based on where the expression inside the absolute value changes sign.

Step 2: Solve for the point where 2𝓍 - 8 = 0. This occurs when 𝓍 = 4. Therefore, the integral can be split into two intervals: [0, 4] and [4, 5].

Step 3: On the interval [0, 4], the expression 2𝓍 - 8 is negative, so |2𝓍 - 8| = -(2𝓍 - 8). On the interval [4, 5], the expression 2𝓍 - 8 is positive, so |2𝓍 - 8| = 2𝓍 - 8.

Step 4: Rewrite the integral as the sum of two integrals: ∫₀⁴ -(2𝓍 - 8)d𝓍 + ∫₄⁵ (2𝓍 - 8)d𝓍. Simplify the integrands in each interval.

Step 5: Compute each integral separately by applying the power rule for integration and evaluating the definite integrals. Combine the results to find the total value of the original integral.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Definite Integrals

A definite integral calculates the accumulation of a quantity, represented as the area under a curve between two specified limits. In this case, the integral ∫₀⁵ |2𝓍―8|d𝓍 evaluates the area between the curve of the function |2𝓍―8| and the x-axis from x=0 to x=5. Understanding how to set up and evaluate definite integrals is crucial for solving problems involving areas and accumulated quantities.

Absolute Value Function

The absolute value function, denoted as |x|, outputs the non-negative value of x regardless of its sign. In the integral ∫₀⁵ |2𝓍―8|d𝓍, the expression inside the absolute value, 2𝓍―8, can be positive or negative depending on the value of x. Identifying where the expression changes sign is essential for correctly evaluating the integral, as it affects the area calculation.

Piecewise Functions

Piecewise functions are defined by different expressions based on the input value. For the integral involving |2𝓍―8|, we need to determine the points where 2𝓍―8 equals zero to split the integral into segments where the function behaves differently. This approach allows us to evaluate the integral accurately by considering the appropriate expression for each segment of the interval.