Chapter 5: Problem 58
In Exercises \(55-62,\) graph the function and find its average value over the given interval. $$ f(x)=3 x^{2}-3 \quad \text { on } \quad[0,1] $$
Short Answer
Expert verified
The average value of the function is -2 over the interval [0, 1].
Step by step solution
01
Understand the Function
The function given is a quadratic function: \( f(x) = 3x^2 - 3 \). We are considering its behavior on the interval \([0, 1]\). The function will be graphed, and its average value will be calculated over this interval.
02
Graphing the Function
To graph the function \( f(x) = 3x^2 - 3 \), start by identifying key points. For example:1. At \( x = 0 \): \( f(0) = 3(0)^2 - 3 = -3 \)2. At \( x = 1 \): \( f(1) = 3(1)^2 - 3 = 0 \)The function is a parabola opening upwards because the coefficient of \(x^2\) is positive. Plot these points and sketch the curve on the interval \([0, 1]\).
03
Determine the Average Value Formula
The average value of a function \( f(x) \) over an interval \([a, b]\) is given by the formula: \[ \frac{1}{b-a} \int_{a}^{b} f(x) \, dx \]For this problem, \( a = 0 \) and \( b = 1 \), hence the average value is:\[ \frac{1}{1-0} \int_{0}^{1} (3x^2 - 3) \, dx \]
04
Integrate the Function
Calculate the integral:\[ \int_{0}^{1} (3x^2 - 3) \, dx = \left[ x^3 - 3x \right]_0^1 \]Evaluate the definite integral by substituting the limits:1. Upper limit: \( (1)^3 - 3(1) = 1 - 3 = -2 \)2. Lower limit: \( (0)^3 - 3(0) = 0 \)Thus, the integral is \( -2 \).
05
Calculate the Average Value
Using the result from the integration step, plug it into the average value formula:\[ \frac{1}{1-0} (-2) = -2 \]Hence, the average value of \( f(x) = 3x^2 - 3 \) over the interval \([0, 1]\) is \(-2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Quadratic Functions
Quadratic functions play a significant role in mathematics. These functions are expressed in the form \( f(x) = ax^2 + bx + c \), where \( a \), \( b \), and \( c \) are constants, and \( a \) is not zero. In our exercise, the function is \( f(x) = 3x^2 - 3 \). This is a simple quadratic function with \( a = 3 \), \( b = 0 \), and \( c = -3 \).
Key characteristics of quadratic functions include:
Key characteristics of quadratic functions include:
- They graph as parabolas, either opening upwards if \( a > 0 \) or downwards if \( a < 0 \).
- The vertex of a parabola is a significant point, representing the minimum or maximum of the function.
- The axis of symmetry can be found using the formula \( x = -\frac{b}{2a} \).
The Role of Definite Integrals
The definite integral is a fundamental concept in calculus. It helps determine the net area under a curve on a specified interval. For the function \( f(x) = 3x^2 - 3 \), the definite integral from \( x = 0 \) to \( x = 1 \) will provide valuable information.
Here’s how integrals assist us:
Here’s how integrals assist us:
- They calculate the net area which may be positive or negative, depending on the position of the graph relative to the x-axis.
- To compute this integral, we evaluate \( \int_{0}^{1} (3x^2 - 3) \, dx \), which involves finding the antiderivative and using it to determine the function's accumulated value between the limits.
- Evaluating the upper and lower limits of this function’s integral results in a final value of \(-2\).
Graphing Functions Efficiently
Graphing functions is a crucial skill for visualizing mathematical concepts. It involves plotting key points and understanding the shape of the function. For the function \( f(x) = 3x^2 - 3 \), graphing within the interval \([0, 1]\) is important for understanding its behavior.
Follow these steps to graph effectively:
Follow these steps to graph effectively:
- Identify and plot key points: At \( x = 0 \), \( f(x) = -3 \) and at \( x = 1 \), \( f(x) = 0 \).
- Sketch the parabola by noting its general shape - in this scenario, it's an upward-opening parabola due to the positive coefficient \( 3 \).
- Ensure that your graph clearly represents the entire curve from \( x = 0 \) to \( x = 1 \).