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IM: 7.5.9: Multiplying Rational Numbers (Lesson)

By Newsela Staff
Last updated 6 days ago
17 Questions
9.1: Before and After
Where was the girl:

5 seconds after this picture was taken?

5 seconds before this picture was taken?

9.2: Backwards in Time
A traffic safety engineer was studying travel patterns along a highway. She set up a camera and recorded the speed and direction of cars and trucks that passed by the camera. Positions to the east of the camera are positive, and to the west are negative.

Here are some positions and times for one car:

In what direction is this car traveling?

What is the car's velocity?

What does it mean when the time is zero?

What could it mean to have a negative time?

A traffic safety engineer was studying travel patterns along a highway. She set up a camera and recorded the speed and direction of cars and trucks that passed by the camera. Positions to the east of the camera are positive, and to the west are negative.

Here are the positions and times for a different car whose velocity is -50 feet per second:

Complete the table with the rest of the positions.

In what direction is this car traveling? Explain how you know.

A traffic safety engineer was studying travel patterns along a highway. She set up a camera and recorded the speed and direction of cars and trucks that passed by the camera. Positions to the east of the camera are positive, and to the west are negative.

Complete the table for several different cars passing the camera.

If a car is traveling east when it passes the camera, will its position be positive or negative 60 seconds before it passes the camera?

If we multiply a positive number and a negative number, is the result positive or negative?

If a car is traveling west when it passes the camera, will its position be positive or negative 60 seconds before it passes the camera?

If we multiply two negative numbers, is the result positive or negative?

9.3: Cruising
Around noon, a car was traveling -32 meters per second down a highway. At exactly noon (when time was 0), the position of the car was 0 meters.

Complete the table.

Graph the relationship between the time and the car's position using the applet:

https://curriculum.illustrativemathematics.org/MS/students/2/5/9/index.html

[Scroll to the tool under "9.3: Cruising"]

What was the position of the car at -3 seconds?

What was the position of the car at 6.5 seconds?

9.4: Rational Numbers Multiplication Grid

Look at the patterns along the rows and columns and continue those patterns to complete the table in the applet. When you have filled in all the boxes you can see, click on the "More Boxes" button.

https://curriculum.illustrativemathematics.org/MS/students/2/5/9/index.html
[Scroll to the tool under "9.4: Rational Numbers Multiplication Grid"]

What does this tell you about multiplication by a negative?