Lesson 16
Elimination
These materials, when encountered before Algebra 1, Unit 2, Lesson 16 support success in that lesson.
Lesson Narrative
The mathematical purpose of this lesson is to work with equivalent equations that are multiples of one another. In the first activity after the warm-up, students examine the effect on the graphs of the equation of multiplying an equation by a constant. In the second activity, students find a value that can multiply an equation to achieve a target coefficient for a given variable. In the associated Algebra lesson, students use the skill of multiplying an equation by a constant when solving systems of equations by elimination.
Students attend to precision (MP6) when they use precise language to describe a reason why a system of equations does not belong. Students look for and make use of structure (MP7) when they recognize two equations to be equivalent.
Learning Goals
Teacher Facing
- Multiply an equation by a number to reach a target coefficient for a given variable.
- Recognize that multiplying an equation by a factor creates an equivalent equation with the same intercepts and slope.
Student Facing
- Let’s learn how to check our thinking when using elimination to solve systems of equations.