# 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.