1. Linear Equations in Two Variables
Lesson 2.6
Creating and Graphing
Linear Equations in Two Variables
Concept: Graphing Linear Equations
EQ: How do I create and graph a linear equation in two variables from a word problem? (Standard CED.2)
Vocabulary: Slope, Y-Intercept, Independent & Dependent Variable
1.3.1: Creating and Graphing Linear Equations in Two Variables

2. Creating & Graphing Linear Equations
Read the problem statement carefully.
Look for the information given and make a list or underline the known quantities.
Determine which information tells you the rate of change, or the slope, m. Look for words such as each, every, per, or rate.
Determine which information tells you the y-intercept, or b. This could be an initial or starting value, a flat fee, and so forth.
Substitute the slope and y-intercept into the linear equation formula, y = mx + b.
Set up the coordinate plane and identify the independent and dependent variables.
Graph the equation by using the slope and y-intercept or by making a table of values.
1.3.1: Creating and Graphing Linear Equations in Two Variables

3. Guided Practice - Example 1
A taxi company in Atlanta charges $2.50 for a ride plus $2 for every mile driven. Write and graph the equation that models the taxi company’s total fees.
Read the problem.
2. Determine the known quantities.
3-4. Identify the slope and the y-intercept.
slope _____ y-intercept ______
Substitute the slope and y-intercept into the equation
y = mx + b, where m is the slope and b is the
y- intercept.
_____________
1.3.1: Creating and Graphing Linear Equations in Two Variables

4. Equation: Example 1, continued y = 2x + 2.50
6. Set up the coordinate plane and identify the independent and dependent variables.
Graph the equation using the slope and y-intercept. Plot the y-intercept first and then use the slope to find the second point.
1.3.1: Creating and Graphing Linear Equations in Two Variables

5. Guided Practice - Example 2
Matthew receives a base weekly salary of $300 plus commission of $50 for each vacuum he sells. Write and graph the equation that models his weekly earnings.
Slope: ________________ y-intercept: _____________
Equation: ___________________
1.3.1: Creating and Graphing Linear Equations in Two Variables

6. Example 2, continued 𝒚=𝟓𝟎𝒙+𝟑𝟎𝟎
Use the y-intercept to help you graph your first point. Use the slope to help you find your second point.
Vacuums sold
1.3.1: Creating and Graphing Linear Equations in Two Variables

7. You Try!
A 12-inch candle burns at a rate of 2 inches per hour. Write and graph the equation that models the height of the candle over time.
Read the problem.
2. Determine the known quantities.
3-4. Identify the slope and the y-intercept.
slope _____ y-intercept ______
Substitute the slope and y-intercept into the equation
y = mx + b, where m is the slope and b is the
y- intercept.
_____________
1.3.1: Creating and Graphing Linear Equations in Two Variables

8. You Try , continued 𝒚=−𝟐𝒙+𝟏𝟐
Use the y-intercept to help you graph your first point. Use the slope to help you find your second point.
Hours
1.3.1: Creating and Graphing Linear Equations in Two Variables

9. Guided Practice - Example 3
A water company charges a monthly fee of $6.70 plus a usage fee of $2.60 per 1,000 gallons used. Write and graph the equation that models the water company’s total fees.
Slope: ________________ y-intercept: _____________
Equation: ___________________
1.3.1: Creating and Graphing Linear Equations in Two Variables

10. Graph the equation by making a table of values.
Example 3, continued
𝒚=𝟐.𝟔𝒙+𝟔.𝟕
Graph the equation by making a table of values. x y 5 7
1.3.1: Creating and Graphing Linear Equations in Two Variables

11. Guided Practice - Example 4
A local convenience store owner spent $10 on pencils to resell at the store. Write and graph the equation of the store’s revenue if each pencil sells for $0.50.
Slope: _____________ y-intercept: _____________
Equation: ___________________
1.3.1: Creating and Graphing Linear Equations in Two Variables

12. Graph the equation by making a table of values.
Example 4, continued
𝒚= 𝟏 𝟐 𝒙−𝟏𝟎
Graph the equation by making a table of values. x y 2 4
1.3.1: Creating and Graphing Linear Equations in Two Variables

13. You Try!
Maddie borrowed $1,250 from a friend to buy a new TV. Her friend doesn’t charge any interest, and Maddie makes $40 payments each month. Write and graph the equation that models the money Maddie owes.
1. Read the problem.
2. Determine the known quantities.
3-4. Identify the slope and the y-intercept.
slope _____ y-intercept ______
Substitute the slope and y-intercept into the equation
y = mx + b, where m is the slope and b is the
y- intercept.
_____________
1.3.1: Creating and Graphing Linear Equations in Two Variables

14. Graph the equation by making a table of values.
You Try, continued
𝒚=−𝟒𝟎𝒙+𝟏𝟐𝟓𝟎
Graph the equation by making a table of values. x y 6 21
1.3.1: Creating and Graphing Linear Equations in Two Variables