Chapter 2: Problem 44
Sketch the graph of the piecewise defined function. $$f(x)=\left\\{\begin{array}{ll}x^{2} & \text { if }|x| \leq 1 \\\1 & \text { if }|x|>1\end{array}\right.$$
Short Answer
Expert verified
The graph consists of a parabola \( f(x) = x^2 \) from \([-1, 1]\) and horizontal lines \( f(x) = 1 \) elsewhere.
Step by step solution
01
Identify the function components
The piecewise function has different rules depending on the value of \( x \). The function \( f(x) = x^2 \) applies for \( |x| \leq 1 \), which means \( x \) is between \(-1\) and \(1\) inclusive. The constant function \( f(x) = 1 \) applies for \( |x| > 1 \).
02
Sketch \( f(x) = x^2 \) for \( |x| \leq 1 \)
For \( x \) values between \(-1\) and \(1\), plot the parabola \( f(x) = x^2 \). At \( x = -1 \), the graph is at \( f(-1) = (-1)^2 = 1 \), at \( x = 0 \), \( f(0) = 0^2 = 0 \), and at \( x = 1 \), \( f(1) = 1^2 = 1 \). These points form a curve that is a section of the parabola.
03
Sketch \( f(x) = 1 \) for \( |x| > 1 \)
For \( x \) less than \(-1\) and greater than \(1\), \( f(x) = 1 \). Thus, draw a horizontal line at \( y = 1 \). The line extends outward from \(-\infty\) to \(-1\) and from \(1\) to \(\infty\).
04
Combine the segments and check continuity
Combine the sketch of the parabola and the horizontal lines. The function is continuous at \( x = -1 \) and \( x = 1 \) since \( x^2 = 1 \) and both pieces join at these points smoothly. Therefore, the graph should look like a parabola restricted to the interval \([-1, 1]\) and flat horizontal segments at \( y = 1 \) outside this interval.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Piecewise Functions
Graphing piecewise functions involves plotting different portions of a function over specified intervals. It requires understanding how each segment behaves in its domain. For this particular problem, the function is broken into two segments: a curve and a line.
- For \(f(x) = x^2\) where \(|x| \leq 1\), a parabola defines the function. This is visualized by plotting points: at \(x = -1\) and \(x = 1\), \(f(x) = 1\). At \(x = 0\), \(f(x) = 0\).
- Outside this range, when \(|x| > 1\), \(f(x) = 1\). This results in a horizontal line for values less than \-1\ otherwise greater than \1\.
Continuity of Piecewise Functions
The concept of continuity in piecewise functions examines whether the function remains uninterrupted across segments. For a function to be continuous, its graph must not have jumps or breaks at the domain transition points.
In this exercise, continuity is checked at the endpoints \(x = -1\) and \(x = 1\), where the function definition changes. Here, \(f(x) = x^2\) connects seamlessly with \(f(x) = 1\), sustaining the same value at these points.
The continuity can be confirmed by checking:
In this exercise, continuity is checked at the endpoints \(x = -1\) and \(x = 1\), where the function definition changes. Here, \(f(x) = x^2\) connects seamlessly with \(f(x) = 1\), sustaining the same value at these points.
The continuity can be confirmed by checking:
- At \(x = -1\) and \(x = 1\), the parabolic segment leads to \(f(x) = 1\). Hence, the horizontal line also reaches \(y = 1\), indicating continuity at the junction.
- Transition involves no sudden jumps, ensuring a smooth connection throughout.
Parabolas in Piecewise Functions
Parabolas often feature in piecewise functions as they represent quadratic relationships. Understanding their shape is key when graphing pieces of these functions. A parabola's basic form, such as \(f(x) = x^2\), is a symmetric curve that opens upwards starting from the vertex at the origin.
When used in piecewise functions, the parabola must fit within its defined segment. For this exercise:
When used in piecewise functions, the parabola must fit within its defined segment. For this exercise:
- The segment where \(|x| \leq 1\) forms a section of \(f(x) = x^2\). Here, the parabola begins at \(-1\), rises to its vertex at \(0\), and descends again through \(1\).
- It is limited to this interval, appearing as just a part of the full quadratic curve.