Chapter 5: Problem 28
If \(f(x)\) is even and \(\int_{-2}^{2}(f(x)-3) d x=8,\) find \(\int_{0}^{2} f(x) d x\).
Short Answer
Expert verified
\( \int_{0}^{2} f(x) \, dx = 10 \).
Step by step solution
01
Understand Even Functions
A function \( f(x) \) is defined as even if it satisfies the condition \( f(-x) = f(x) \) for all \( x \). This property implies that the graph of an even function is symmetric about the y-axis.
02
Apply Symmetry Property
For even functions, the integral from \(-a\) to \(a\) can be expressed as twice the integral from \(0\) to \(a\). Therefore, \( \int_{-2}^{2} f(x) dx = 2 \int_{0}^{2} f(x) dx \).
03
Extract Given Information
From the problem, we have \( \int_{-2}^{2} (f(x) - 3) \, dx = 8 \). We can separate this into two integrals: \( \int_{-2}^{2} f(x) \, dx - \int_{-2}^{2} 3 \, dx = 8 \).
04
Calculate the Integral of Constant 3
Compute \( \int_{-2}^{2} 3 \, dx \). This integral is simply \( 3x \) evaluated from \(-2\) to \(2\), resulting in \( 3(2 - (-2)) = 3 \times 4 = 12 \).
05
Solve for \( \int_{-2}^{2} f(x) \, dx \)
Substitute back in to solve for \( \int_{-2}^{2} f(x) \, dx \): \( \int_{-2}^{2} f(x) \, dx - 12 = 8 \). Therefore, \( \int_{-2}^{2} f(x) \, dx = 20 \).
06
Find \( \int_{0}^{2} f(x) \, dx \)
Using the symmetry property from Step 2, we know \( \int_{-2}^{2} f(x) \, dx = 2 \int_{0}^{2} f(x) \, dx \). Therefore,\( 2 \int_{0}^{2} f(x) \, dx = 20 \). Divide by 2 to find \( \int_{0}^{2} f(x) \, dx = 10 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integral Calculus
Integral Calculus is a fundamental concept in mathematics that deals with the accumulation of quantities. It allows us to find the total value of a function over a given interval. When we talk about integrating a function, we are discussing the process of summing infinitesimally small quantities to arrive at a total quantity, such as area under a curve. This process can be represented symbolically by an integral sign, \(\int\), followed by the function and the interval of integration.
- The integrals can be indefinite, which represent general antiderivatives and include integration constants.
- They can also be definite, where we evaluate the integral between specific lower and upper bounds to get a numerical value.
Symmetry Properties
Symmetry properties in mathematics help simplify the process of solving integrals, especially when dealing with even functions. When a function is symmetric about a line or a point, it can lead to simplifications in the analysis and calculation of integrals.
For even functions, \(f(x) = f(-x)\), the graph of the function is symmetric about the y-axis. One key property associated with this symmetry is:
For even functions, \(f(x) = f(-x)\), the graph of the function is symmetric about the y-axis. One key property associated with this symmetry is:
- If \(f(x)\) is even over an interval \([-a, a]\), then \(\int_{-a}^{a} f(x) \, dx = 2 \int_{0}^{a} f(x) \, dx.\)
Definite Integrals
Definite Integrals are a type of integral in calculus that produce a specific numerical value. When evaluating a definite integral, we calculate the integral of a function over a specified interval, providing a concrete result. The notation \(\int_{a}^{b} f(x) \, dx\) represents the integral of a function \(f(x)\) from a lower bound \(a\) to an upper bound \(b\).
- Definite integrals are helpful in determining the area under a curve between two points.
- Since they result in a number, they can act as a measure for various physical quantities like displacement, total energy, or total mass.