Mathematics
Grade 8
15 min
Write a linear function from a table
Write a linear function from a table
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1
Introduction & Learning Objectives
Learning Objectives
Identify independent and dependent variables in a table of values.
Calculate the rate of change (slope) from a given table.
Determine the y-intercept of a linear function from a table or by calculation.
Write a linear function in slope-intercept form ($y = mx + b$) given a table of values.
Verify if a given table represents a linear relationship.
Use a derived linear function to predict values not explicitly shown in the table.
Ever wonder how scientists predict future trends or how businesses forecast sales? 📈 It often starts with understanding patterns in data!
In this lesson, you'll learn how to take a set of data presented in a table and turn it into a powerful mathematical rule called a linear function. This skill helps us describe relationshi...
2
Key Concepts & Vocabulary
TermDefinitionExample
Linear FunctionA function whose graph is a straight line. It describes a relationship where the dependent variable changes at a constant rate with respect to the independent variable.The relationship between the number of hours you work and the total money you earn at a fixed hourly wage.
Table of ValuesAn organized list that shows the relationship between two variables, typically an input (x) and an output (y).A table showing (hours worked, money earned): (1, $10), (2, $20), (3, $30).
Independent Variable (x)The input variable whose value can be chosen freely or changes independently. It's usually represented on the horizontal axis.In a table of (time, distance), 'time' is the independent variable.
Dependent Variable (y)The output variable whose value...
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Core Formulas
Slope Formula
$m = \frac{\text{change in y}}{\text{change in x}} = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1}$
Use this formula to calculate the slope (m) of a linear function given any two distinct points $(x_1, y_1)$ and $(x_2, y_2)$ from the table. It represents the constant rate of change.
Slope-Intercept Form of a Linear Equation
$y = mx + b$
Once you have found the slope (m) and the y-intercept (b), substitute these values into this form to write the complete linear function. This equation allows you to find any y-value for a given x-value.
5 more steps in this tutorial
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Challenging
The table below represents a linear relationship. What is the missing value for y that maintains this relationship?
x | y
--|--
2 | 3
5 | 12
7 | ?
A.18
B.15
C.21
D.17
Challenging
Consider the two linear functions represented by Table A and Table B. Which statement is true?
Table A: x: 1, 2; y: 5, 9
Table B: x: 2, 4; y: 3, 13
A.The function in Table A has a steeper slope.
B.The function in Table B has a steeper slope.
C.Both functions have the same slope.
D.The function in Table A has a greater y-intercept.
Challenging
The following table represents a linear function, but the change in x is not constant. What is the equation for this function?
x | y
--|--
1 | -2
3 | 8
7 | 28
A.y = 10x - 12
B.y = 4x - 6
C.y = 5x - 7
D.y = 5x + 3
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