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...
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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.

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Sample Practice Questions

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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