What is the primary goal of using either substitution or elimination when solving a system of linear equations?

To reduce the system to a single equation with one variable.

In the elimination method, why is it sometimes necessary to multiply one or both equations by a constant?

To make the coefficients of one variable opposites so they cancel out when the equations are added.

Explain why multiplying an equation by a constant does not change the solution to the system.

Multiplying an equation by a constant is the same as multiplying both sides of the equation by the same number, maintaining the equality and thus the solution.

When using elimination, if you add the equations and both variables are eliminated, resulting in a true statement (e.g., 0 = 0), what does this indicate about the system of equations?

The system has infinitely many solutions.

Solving Systems of Equations

9th GradeMath90 min

Learning Objective

I can solve systems of linear equations using substitution and elimination.

Lesson Flow

Watch Video

10 min

Using Elimination to Solve Systems

Brian McLogan

Guided Notes

18 min

Key concepts students will learn:

•
The elimination technique involves adding two equations together in a way that one of the variables is eliminated.
•
To eliminate a variable, you may need to multiply one or both equations by a constant so that the coefficients of one variable are opposites.
•
Once you solve for one variable, you can substitute that value back into either of the original equations to solve for the other variable.

Practice

27 min

12 questions • Multiple choice & Short answer

Exit Ticket

5 min

“Solve the following system of equations using elimination: 4x + 3y = 10 and 2x - y = 2. Show all your work.”

Teacher Guide

Get the complete package:

Answer keys for all questions
Differentiation strategies
Extension activities
Printable student handouts

Solving Systems of Equations

Learning Objective

Lesson Flow

Watch Video

Guided Notes

Practice

Exit Ticket

Teacher Guide

New to Insta~Lesson?

About Insta~Lesson

How Insta~Lesson Helps Teachers Plan

How Insta~Lesson Supports Instruction Schoolwide