Problem preview
A-REI.5 Warmup M1-011-A05-V01

Justify elimination: replacing one equation in a two-variable system with a linear combination preserves solutions.

Find a multiplier to eliminate a variable

Problem

What multiplier could you use on one equation to eliminate \(y\) in the system \(2x~+~3y~=~12\), \(5x~-~y~=~7\)?

Big Picture

What this problem is really about

The useful multiplier is the one that makes a chosen pair of variable coefficients opposites. We’ll compare the coefficients, set their sum after scaling equal to zero, and apply the resulting multiplier to every term of the affected equation, including its constant. Adding the scaled rows then verifies whether the targeted variable truly disappears.

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Four variants of this problem type
Curriculum context
Course
Math I
Standard
A-REI.5
Category
Algebra
Domain
Reasoning with Equations and Inequalities
Objective
Justify elimination: replacing one equation in a two-variable system with a linear combination preserves solutions.
Problem type
Find a multiplier to eliminate a variable