Chapter 2: Problem 51
For the following exercises, which of the tables could represent a linear function? For each that could be linear, find a linear equation that models the data.
Short Answer
Expert verified
Identify constant slopes; if found, use them to find a linear equation.
Step by step solution
01
Analyzing the Table for Linear Relationships
To determine if a table represents a linear function, check if there is a constant rate of change between the x-values and y-values. This means the difference in y divided by the difference in x (i.e., the slope) should be constant for all pairs of consecutive data points in the table. For instance, if a table has points \( (x_1, y_1), (x_2, y_2), (x_3, y_3) \), then the slope should be \( \frac{y_2 - y_1}{x_2 - x_1} = \frac{y_3 - y_2}{x_3 - x_2} \).
02
Calculating the Slope
Calculate the slope (m) using two consecutive data points from the table. For example, if the table gives the points (1, 2), (3, 6), then:\[m = \frac{6 - 2}{3 - 1} = \frac{4}{2} = 2\]This indicates that for each increase in x by 1 unit, y increases by 2 units.
03
Forming the Linear Equation
Once a constant slope is confirmed, use one of the points and the slope to write the equation of the line in the slope-intercept form: \( y = mx + b \). Substitute the slope and coordinates from one point to find the y-intercept (b). Using the point (1, 2) and slope (2):\[2 = 2 \cdot 1 + b \]\[b = 0\]The linear equation is \( y = 2x \).
04
Verifying the Equation
Verify the linear equation by checking all points in the table to ensure they satisfy the equation \( y = 2x \). Substituting the x-values from the table into the equation should yield the corresponding y-values as given in the table.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope Calculation
To calculate the slope, which is a key component of understanding linear functions, we need to find the rate at which the y-values change with respect to the x-values. This change is measured between two consecutive points on the graph of the function. The slope is expressed as the ratio of the difference in y-coordinates to the difference in x-coordinates. Mathematically, if you have two points,
- Point 1: \(x_1, y_1\)
- Point 2: \(x_2, y_2\)
Rate of Change
The rate of change is an important concept connected to slope in linear functions. It describes how a quantity changes over time. In the context of a linear function, this change is constant and is the same as the slope we calculate.
This constant rate of change indicates how much the dependent variable (often y) changes for a unit increase in the independent variable (often x). For example, if the slope \(m\) is 2, it means that when x increases by 1, y increases by 2.
This constant rate of change indicates how much the dependent variable (often y) changes for a unit increase in the independent variable (often x). For example, if the slope \(m\) is 2, it means that when x increases by 1, y increases by 2.
- Constant rate of change = Linearity
- Rate of change = Slope = Steepness of Line
Slope-Intercept Form
When we express a linear equation, one of the most common forms used is the slope-intercept form. This form makes it easy to see both the slope and where the line crosses the y-axis. The general form of a linear equation in slope-intercept form is:\[y = mx + b\]where \(m\) represents the slope of the line, and \(b\) represents the y-intercept, the point where the line crosses the y-axis.
This form is particularly useful because:
This form is particularly useful because:
- \(m\) directly shows the rate of change.
- \(b\) provides information on starting values.
Verifying Linear Equations
After finding an equation that seems to fit the data from a table, it’s important to verify its accuracy. Verification ensures that all data points in the table satisfy the equation you formed. This means substituting each x-value in the equation should yield the corresponding y-value in the table.
For example, if your equation is \( y = 2x \) and you have a point (1, 2) from your table:
For example, if your equation is \( y = 2x \) and you have a point (1, 2) from your table:
- Substitute x = 1 into the equation: \( y = 2(1) = 2 \)
- The output matches the y-value (2) of the point (1, 2)