Chapter 2: Problem 111
Consider the piecewise-defined function \(f\) defined by:
\(f(x)=\left\\{\begin{array}{ll}x^{2}+2, & \text { for }-2 \leq x \leq 0 \\ 2,
& \text { for } 0
Short Answer
Expert verified
The absolute maximum is 6 at \( x = -2\). The absolute minimum is 2.
Step by step solution
01
Understand the Function Definition
The function is defined in three different intervals. For \( -2 \leq x \leq 0 \), \( f(x) = x^2 + 2 \); for \( 0 < x < 4 \), \( f(x) = 2 \); and for \( 4 \leq x \leq 6 \), \( f(x) = x - 2 \).
02
Sketch Each Segment of the Graph
1. For \( -2 \leq x \leq 0 \), plot the quadratic function \( x^2 + 2 \). This segment is a part of the parabola with vertex at (0, 2).\2. For \( 0 < x < 4 \), plot the constant function \( f(x) = 2 \), which is a horizontal line. This line does not include the endpoints.\3. For \( 4 \leq x \leq 6 \), plot the linear function \( f(x) = x - 2 \). This is a line starting from (4, 2) to (6, 4).
03
Identify the Absolute Maximum
Evaluate the endpoints and any continuous segments:\- At \( x = -2 \), \( f(-2) = (-2)^2 + 2 = 6 \).\- At \( x = 4 \), \( f(4) = 4 - 2 = 2 \).\- At \( x = 6 \), \( f(6) = 6 - 2 = 4 \).\The maximum value is at \( f(-2) = 6 \).
04
Describe the Absolute Minimum
The minimum value can be found by comparing all segments:\- The quadratic part, \( f(x) = x^2 + 2 \), has a minimum value of 2 when \( x = 0 \).\- The constant part, \( f(x) = 2 \), also equals 2 on \( 0 < x < 4 \).\- The linear part, \( f(x) = x - 2 \), reaches its minimum value at \( x = 4 \) which is 2.\Thus, the absolute minimum value is 2.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Piecewise Functions
A piecewise-defined function is one that has different expressions based on the input value. For example, consider the function provided: \[f(x) = \begin{cases} x^2 + 2, & \text{for } -2 \leq x \leq 0 \ 2, & \text{for } 0 < x < 4 \ x - 2, & \text{for } 4 \leq x \leq 6 \end{cases} \] To graph such a function:
- Identify the distinct intervals.
- Plot each section of the function accordingly.
- For \(-2 \leq x \leq 0\), the graph is a part of a parabola \(y = x^2 + 2\).
- For \(0 < x < 4\), the function is simply \(y = 2\), which is a horizontal line.
- From \(4 \leq x \leq 6\), the function becomes linear with \(y = x - 2\).
Absolute Maximum
To determine the absolute maximum of a piecewise function, evaluate the function at critical points and endpoints within the domain. For the provided function, evaluate:
- At \(x = -2\), \[f(-2) = (-2)^2 + 2 = 6\]
- At \(x = 4\), \[f(4) = 4 - 2 = 2\]
- At \(x = 6\), \[f(6) = 6 - 2 = 4\]
Absolute Minimum
For the absolute minimum, you must consider the function values across its entire domain. For each segment of the given function:
- Over the interval \(-2 \leq x \leq 0\), the minimum of \[f(x) = x^2 + 2\] occurs at \(x = 0\) giving \[f(0) = 2\].
- Over \(0 < x < 4\), the constant function \[f(x) = 2\] maintains the value of 2.
- From \(4 \leq x \leq 6\), the function \[f(x) = x - 2\] at \(x = 4\) is also 2.
Function Evaluation
Function evaluation involves substituting specific values for \(x\) into the function \(f(x)\) and solving. For piecewise functions:
- Identify the applicable sub-function based on the \(x\) value.
- Perform the substitution and simplify.