CCSS.Math.Content.HSA-CED.A.3

MathGrades 9–12Creating Equations

The standard

Represent constraints by equations or inequalities, and by systems of equations and/or inequalities, and interpret solutions as viable or nonviable options in a modeling context.

Common Core State Standards for Mathematics

What this standard means

Students need to turn limits from a situation into equations, inequalities, or systems. They should name variables, write constraints, graph or solve them, and connect the solution set back to the context.

Mastery means students can explain why a point works or does not work, not just shade a graph. They should notice limits like whole numbers, nonnegative values, budgets, maximums, minimums, and capacity. Common stuck points are mixing up inequality signs, forgetting units, treating every algebraic solution as realistic, and not checking answers against every condition in the problem.

Ways to teach it

  • Hands-on activity: Give pairs a snack budget and nutrition labels, then have them write inequalities for cost, calories, and protein.
  • Discussion prompt: Ask, “Which solution points make sense in real life, and which ones only work on the graph?”
  • Quick assessment: Show three ordered pairs for a two-constraint system and ask students to label each viable or not with one reason.
  • Real-world connection: Use phone plan data limits and monthly costs to write constraints and compare which plans fit different users.

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Related standards

Standard text verified against corestandards.org on July 10, 2026.

Page updated July 10, 2026.

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