Chapter 3: Problem 7
Sketch the graph of the function by first making a table of values. \(f(x)=2 x-4\)
Short Answer
Expert verified
Plot points for \(x = -2, -1, 0, 1, 2\), then draw a line through them.
Step by step solution
01
Choose Values for x
To begin sketching the graph of the function, select a range of values for \(x\). This range should cover both negative and positive numbers to provide a comprehensive view of the graph. We will choose \(-2, -1, 0, 1, 2\) as our values for \(x\).
02
Calculate Corresponding f(x) Values
Substitute each chosen \(x\) value into the function \(f(x) = 2x - 4\) to find the corresponding \(f(x)\) values. 1. For \(x = -2\): \(f(-2) = 2(-2) - 4 = -4 - 4 = -8\) 2. For \(x = -1\): \(f(-1) = 2(-1) - 4 = -2 - 4 = -6\) 3. For \(x = 0\): \(f(0) = 2(0) - 4 = 0 - 4 = -4\) 4. For \(x = 1\): \(f(1) = 2(1) - 4 = 2 - 4 = -2\) 5. For \(x = 2\): \(f(2) = 2(2) - 4 = 4 - 4 = 0\)
03
Create a Table of Values
Now, organize the \(x\) values and their corresponding \(f(x)\) values into a table:\(\begin{array}{c|c} x & f(x) \\hline-2 & -8 \-1 & -6 \ 0 & -4 \ 1 & -2 \ 2 & 0 \\end{array}\)This table will help us plot points on a coordinate plane.
04
Plot Points on a Coordinate Plane
Use the values from the table to plot points on a coordinate plane as follows:
- Plot the point (-2, -8).
- Plot the point (-1, -6).
- Plot the point (0, -4).
- Plot the point (1, -2).
- Plot the point (2, 0).
These points represent the graph of the function.
05
Draw the Line
Once the points are plotted, draw a straight line through them. This line represents the function \(f(x) = 2x - 4\). Ensure the line extends in both directions beyond the plotted points to indicate it continues indefinitely.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Making a Table of Values
In order to graph a linear function, creating a table of values is a particularly useful step. This involves selecting a set of values for the variable \(x\), then calculating the corresponding \(f(x)\) values using the given function. In our example with the function \(f(x) = 2x - 4\), we chose the \(x\)-values \(-2, -1, 0, 1, 2\).
- Start by selecting a mix of positive and negative numbers as well as zero to get a comprehensive idea of how the graph behaves.
- Substitute each \(x\) into the linear equation to find its corresponding \(f(x)\).
Plotting Points on a Graph
Once you have your table of values, the next step is to plot these points on a graph. Placing them on a grid helps to visualize the relationship defined by the linear function. On the coordinate plane:
- Each point is an \((x, f(x))\) or \((x, y)\) pair, as derived from our table.
- Plot these points on the graph, marking where each pair lands on the grid.
- Plot point \((-2, -8)\) by moving left 2 units and down 8 units from the origin.
- Do this for all other values: \((-1, -6)\), \((0, -4)\), \((1, -2)\), and \((2, 0)\).
Understanding the Coordinate Plane
The coordinate plane, sometimes called the Cartesian plane, is a two-dimensional plane featuring a horizontal axis (x-axis) and a vertical axis (y-axis), which intersect at the origin. It is crucial for graphing linear functions:
- The x-axis represents the independent variable, \(x\).
- The y-axis represents the dependent variable, \(f(x)\) or \(y\).
Exploring Linear Equations
A linear equation is an algebraic equation in which each term is either a constant or the product of a constant and a single variable. Linear equations graph as straight lines and are defined by expressions such as \(f(x) = 2x - 4\). Let's break it down:
- The \(x\)-coefficient, 2, indicates the slope of the line, or how steep it is.
- The constant term, -4, represents the y-intercept, i.e., where the line crosses the y-axis.