Chapter 2: Problem 12
A function \(f\) is given. (a) Sketch a graph of \(f .\) (b) Use the graph to find the domain and range of \(f\). $$f(x)=3 x-2$$
Short Answer
Expert verified
The domain and range of the function \( f(x) = 3x - 2 \) are both \( (-\infty, \infty) \).
Step by step solution
01
Understand the Function Type
The given function is \( f(x) = 3x - 2 \). This is a linear function because it is in the form of \( f(x) = mx + b \) where \( m = 3 \) (slope) and \( b = -2 \) (y-intercept).
02
Sketch the Graph
To plot the graph of \( f(x) = 3x - 2 \), begin by identifying the y-intercept, which is the point where \( x = 0 \). Here, \( f(0) = 3(0) - 2 = -2 \), so the y-intercept is (0, -2). Next, using the slope \( m = 3 \), move up 3 units and 1 unit to the right starting from the y-intercept to plot another point. Therefore, from (0, -2), the next point is (1, 1). Draw a straight line through these points extending in both directions.
03
Determine the Domain
The domain of a linear function like \( f(x) = 3x - 2 \) is all real numbers because you can input any real number into the function. Therefore, the domain is \( (-\infty, \infty) \).
04
Determine the Range
The range of a linear function is also all real numbers since the value of \( f(x) \) can take any real number depending on the value of \( x \). Therefore, the range is \( (-\infty, \infty) \).
05
Conclusion
From the graph of \( f(x) = 3x - 2 \), we confirm that it is a straight line. Thus, the domain covers all x-values from negative to positive infinity, and the range covers all y-values, also from negative to positive infinity.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Graphs
A function graph visually represents the relationship between the input and output of a function. For a linear function like \( f(x) = 3x - 2 \), its graph is a straight line. This happens because linear functions have a constant rate of change or a constant slope.
To sketch the graph, we need two main things: the slope and the y-intercept. The slope, in our function, is 3, which shows the line rises 3 units upwards for each 1 unit it goes to the right. The y-intercept is -2, which means the line crosses the y-axis at (0, -2).
Here is how you would plot this.
To sketch the graph, we need two main things: the slope and the y-intercept. The slope, in our function, is 3, which shows the line rises 3 units upwards for each 1 unit it goes to the right. The y-intercept is -2, which means the line crosses the y-axis at (0, -2).
Here is how you would plot this.
- Start at the y-intercept (0, -2).
- From (0, -2), making use of the slope, move 3 units up and 1 unit to the right to locate another point on the line, which would be (1, 1).
- Draw a straight line through these two points to extend in both directions infinitely.
Domain and Range
Understanding the domain and range of a function is crucial as it informs us about what values the function can handle and what outputs it can produce.
For linear functions like \( f(x) = 3x - 2 \), the domain is the set of all possible x-values. Since you can input any real number into a linear equation without restrictions, the domain of this function is all real numbers. This is represented as \( (-\infty, \infty) \).
The range, on the other hand, refers to the set of possible y-values. For a linear function that extends infinitely in both vertical directions, this encompasses all real numbers as well. Therefore, just like the domain, the range is \( (-\infty, \infty) \).
This means for every real number input into \( f(x) \), there is a corresponding real number output, depicted by the graph covering every y-value.
For linear functions like \( f(x) = 3x - 2 \), the domain is the set of all possible x-values. Since you can input any real number into a linear equation without restrictions, the domain of this function is all real numbers. This is represented as \( (-\infty, \infty) \).
The range, on the other hand, refers to the set of possible y-values. For a linear function that extends infinitely in both vertical directions, this encompasses all real numbers as well. Therefore, just like the domain, the range is \( (-\infty, \infty) \).
This means for every real number input into \( f(x) \), there is a corresponding real number output, depicted by the graph covering every y-value.
Graphing Techniques
Graphing techniques are often used to accurately represent mathematical functions visually. Here's a simple guide.
When graphing linear functions such as \( f(x) = 3x - 2 \), follow these steps:
When graphing linear functions such as \( f(x) = 3x - 2 \), follow these steps:
- Identify the y-intercept from the function equation. In our case, it's -2.
- Plot the y-intercept on the graph at (0, -2).
- Use the slope to find another point. The slope tells you to move up 3 and right 1 from the y-intercept to find the next point, (1, 1).
- Draw a line through these two points. Ensure it extends across the entire graph, as it represents all possible values of x and y.