Chapter 4: Problem 36
Make a hand-drawn graph. Be sure to label all the asymptotes. List the domain and the \(x\) -intercepts and the \(y\) -intercepts. Check your work using \(a\) graphing calculator. $$f(x)=-\frac{6}{x}$$
Short Answer
Expert verified
Domain: \( (-\infty, 0) \cup (0, +\infty) \).No intercepts.Asymptote: \( x = 0 \).
Step by step solution
01
- Identify the Asymptotes
For the function \( f(x) = -\frac{6}{x} \), identify the vertical and horizontal asymptotes. The vertical asymptote occurs where the denominator is zero, which is at \( x = 0 \). There is no horizontal asymptote for rational functions of this form, but we should consider the behavior as \( x \) approaches \( \infty \) and \( -\infty \).
02
- Determine the Domain
The domain of \( f(x) = -\frac{6}{x} \) is all real numbers except \( x = 0 \), where the function is undefined. So, the domain is: \( (-\infty, 0) \cup (0, +\infty) \).
03
- Find the Intercepts
To find the \( x \)-intercepts, set \( f(x) = 0 \): \[ -\frac{6}{x} = 0 \] Since there is no value of \( x \) which makes this true, there are no \( x \)-intercepts. To find the \( y \)-intercepts, set \( x = 0 \). However, since \( x = 0 \) is not in the domain, there are no \( y \)-intercepts either.
04
- Graph the Function
Graph the function with the identified asymptotes and characteristics. Since \( f(x) = -\frac{6}{x} \) is a hyperbola, draw the graph approach the vertical asymptote at \( x = 0 \) and showing that \( f(x) \to 0 \) as \( x \to \infty \) or \( x \to -\infty \).
05
- Verify with Graphing Calculator
Use a graphing calculator to check the graph and confirm the location of the asymptotes and the shape of the hyperbola.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Domain of a Function
The domain of a function represents all the possible input values (usually termed as 'x') that the function can accept without becoming undefined. For the function \( f(x) = -\frac{6}{x} \), the denominator cannot be zero because division by zero is undefined. This means that at \( x = 0 \), the function is not defined. Therefore, the domain of \( f(x) = -\frac{6}{x} \) is all real numbers except zero, which can be written mathematically as: \( (-\infty, 0) \cup (0, +\infty) \).
In this context, remember:
In this context, remember:
- Functions often have domains restricted by denominators
- Always check for values that cause the function to be undefined
x-intercepts and y-intercepts
Intercepts are the points where the graph of a function crosses the x-axis or y-axis. To find the x-intercepts, set the function equal to zero and solve for x. For \( f(x) = -\frac{6}{x} \): \[ -\frac{6}{x} = 0 \]
This can never be true since \( -\frac{6}{x} \) can only approach zero but not equal zero. Therefore, there are no x-intercepts for this function.
Now, to find the y-intercepts, set \( x = 0 \). However, since x = 0 is not in the domain of \( f(x) = -\frac{6}{x} \), there are no y-intercepts either.
This can never be true since \( -\frac{6}{x} \) can only approach zero but not equal zero. Therefore, there are no x-intercepts for this function.
Now, to find the y-intercepts, set \( x = 0 \). However, since x = 0 is not in the domain of \( f(x) = -\frac{6}{x} \), there are no y-intercepts either.
- x-intercepts occur where the function crosses the x-axis
- y-intercepts occur where the function crosses the y-axis
- Always check if x = 0 is within the domain when looking for y-intercepts
Graphing Rational Functions
When graphing rational functions like \( f(x) = -\frac{6}{x} \), it's important to identify key characteristics such as asymptotes and intercepts. Here is how to graph the function:
- Identify vertical and horizontal asymptotes. For \( f(x) = -\frac{6}{x} \), the vertical asymptote is at \( x = 0 \) because the function is undefined there. Horizontal asymptotes describe the function's behavior as \( x \to \infty \) or \( x \to -\infty \).
- Evaluate the function at critical points and plot a few points to see the general shape.
- Draw the graph approaching the asymptotic lines without crossing them. For \( f(x) = -\frac{6}{x} \), this is a hyperbola that shifts towards the vertical asymptote at \( x = 0 \).
Asymptotic Behavior
Asymptotic behavior describes how a function behaves as the input values approach certain critical points, typically involving infinity or undefined points. For \( f(x) = -\frac{6}{x} \), the key considerations are vertical and horizontal asymptotes:
- The vertical asymptote occurs where the function is undefined. For example, \( x = 0 \)
- While there may not be a traditional horizontal asymptote, it's still valuable to consider the behavior as \( x \to \infty \) or \( x \to -\infty \). For this function, as x increases, \( f(x) \to 0 \).
- Vertical asymptotes indicate unbounded behavior near specific x-values.
- Horizontal or other asymptotes describe how the function behaves at extreme values of x.