Math Problem Statement

Let f be an odd function defined for all real numbers. Which of the following are equal to ∫_2^4 f(x) dx?

Solution

To determine which of the following integrals are equal to 24f(x)dx\int_2^4 f(x) \, dx, given that ff is an odd function, let's review some properties of odd functions and definite integrals.

  1. Odd Function Property: If f(x)f(x) is odd, then f(x)=f(x)f(-x) = -f(x).
  2. Integral Symmetry Property for Odd Functions: For any odd function f(x)f(x), the integral from a-a to aa is zero: aaf(x)dx=0\int_{-a}^a f(x) \, dx = 0
  3. Integral with Negative Limits: For an odd function, if you reverse the limits of integration (e.g., from aa to b-b), you negate the value of the integral: abf(x)dx=abf(x)dx\int_{-a}^b f(x) \, dx = -\int_a^b f(x) \, dx

Given 24f(x)dx\int_2^4 f(x) \, dx, let's analyze the options:

Options Analysis:

  1. 24f(x)dx\int_2^4 f(x) \, dx — This is the original integral, so it is equal to itself.

  2. 24f(x)dx\int_{-2}^4 f(x) \, dx — This integral spans from 2-2 to 44, and we can split it as: 24f(x)dx=22f(x)dx+24f(x)dx\int_{-2}^4 f(x) \, dx = \int_{-2}^2 f(x) \, dx + \int_2^4 f(x) \, dx Since f(x)f(x) is odd, 22f(x)dx=0\int_{-2}^2 f(x) \, dx = 0. Thus: 24f(x)dx=24f(x)dx\int_{-2}^4 f(x) \, dx = \int_2^4 f(x) \, dx So, this option is equal to 24f(x)dx\int_2^4 f(x) \, dx.

  3. 42f(x)dx\int_{-4}^{-2} f(x) \, dx — This integral is in the range from 4-4 to 2-2, so it doesn’t directly relate to the interval 22 to 44, and there’s no direct relationship here that would make it equal to 24f(x)dx\int_2^4 f(x) \, dx.

  4. 42f(x)dx\int_{-4}^2 f(x) \, dx — Similar to option 2, we can split it: 42f(x)dx=42f(x)dx+22f(x)dx\int_{-4}^2 f(x) \, dx = \int_{-4}^{-2} f(x) \, dx + \int_{-2}^2 f(x) \, dx Again, ( \int_{-2}^2 f(x) \

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Math Problem Analysis

Mathematical Concepts

Odd Functions
Definite Integrals
Symmetry Properties of Functions

Formulas

f(-x) = -f(x) for odd functions
∫_{-a}^a f(x) dx = 0 for odd functions
∫_a^b f(x) dx = -∫_{-a}^{-b} f(x) dx

Theorems

Odd Function Property
Integral Symmetry Property for Odd Functions

Suitable Grade Level

College Level Calculus