Math Problem Statement

Given integral subscript short dash 4 end subscript superscript 11 f left parenthesis x right parenthesis d x equals 34 and integral subscript short dash 4 end subscript superscript 11 g left parenthesis x right parenthesis d x equals short dash 5, find the following:

integral subscript 11 superscript short dash 4 end superscript left square bracket 4 f left parenthesis x right parenthesis minus 3 g left parenthesis x right parenthesis right square bracket d x

Solution

To solve the given integral:

114[4f(x)3g(x)]dx,\int_{11}^{-4} [4f(x) - 3g(x)] \, dx,

we need to make use of the properties of integrals and the given values:

411f(x)dx=34\int_{-4}^{11} f(x) \, dx = 34 411g(x)dx=5\int_{-4}^{11} g(x) \, dx = -5

First, let's apply the property of integral limits. Changing the limits of integration will change the sign of the integral:

abh(x)dx=bah(x)dx\int_{a}^{b} h(x) \, dx = -\int_{b}^{a} h(x) \, dx

Thus,

114f(x)dx=411f(x)dx\int_{11}^{-4} f(x) \, dx = -\int_{-4}^{11} f(x) \, dx 114f(x)dx=34\int_{11}^{-4} f(x) \, dx = -34

Similarly,

114g(x)dx=411g(x)dx\int_{11}^{-4} g(x) \, dx = -\int_{-4}^{11} g(x) \, dx 114g(x)dx=5\int_{11}^{-4} g(x) \, dx = 5

Now we can use the linearity of the integral to split it into parts:

114[4f(x)3g(x)]dx=4114f(x)dx3114g(x)dx\int_{11}^{-4} [4f(x) - 3g(x)] \, dx = 4 \int_{11}^{-4} f(x) \, dx - 3 \int_{11}^{-4} g(x) \, dx

Substituting the values we have calculated:

4114f(x)dx=4(34)=1364 \int_{11}^{-4} f(x) \, dx = 4(-34) = -136 3114g(x)dx=3(5)=15-3 \int_{11}^{-4} g(x) \, dx = -3(5) = -15

Adding these results together:

114[4f(x)3g(x)]dx=13615=151\int_{11}^{-4} [4f(x) - 3g(x)] \, dx = -136 - 15 = -151

Therefore, the value of the integral is:

114[4f(x)3g(x)]dx=151\int_{11}^{-4} [4f(x) - 3g(x)] \, dx = -151

Would you like any further details or have any questions?

Here are 5 more questions you might find interesting:

  1. How do you find the derivative of a product of two functions?
  2. What are the rules for integration by parts?
  3. How can you determine the convergence of an improper integral?
  4. What is the Fundamental Theorem of Calculus?
  5. How do you solve a differential equation using separation of variables?

Tip: When solving integrals, always consider whether you can simplify the problem using symmetry, linearity, or known values of integrals over the same interval.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Linearity of Integrals
Properties of Definite Integrals

Formulas

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Theorems

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Suitable Grade Level

Advanced High School or College