CCSS.Math.Content.HSA-REI.B
The standard
Solve equations and inequalities in one variable
Common Core State Standards for Mathematics · High School — Algebra
What this standard means
Students need to solve one-variable equations and inequalities and explain each move as keeping the solution set the same. They should handle linear equations, inequalities, absolute value cases, quadratics, and equations with radicals or rational expressions when they appear in the course.
Mastery looks like choosing a sensible method, showing clean steps, checking for extraneous answers, and writing inequality answers with correct symbols or interval notation. Students often get stuck when multiplying or dividing inequalities by negatives, splitting absolute value cases, clearing fractions, or forgetting that squaring both sides can create false solutions.
Ways to teach it
- Hands-on activity: Give pairs equation cards and solution-step cards, then have them build a correct flow and justify each move aloud.
- Discussion or writing prompt: Ask, “Which step keeps the same solutions, and which step might create extra solutions?” using a radical equation.
- Quick assessment: Put four solved inequalities on the board, two with sign errors, and have students mark and correct the first wrong step.
- Real-world connection: Use a phone plan cost limit to write and solve an inequality for the number of gigabytes a student can use.
Plan a lesson for CCSS.Math.Content.HSA-REI.B
Generate a complete lesson plan aligned to this standard, with objectives, activities, and materials. Free, no account needed.
Related standards
- CCSS.Math.Content.HSA-REI.B.4
Solve quadratic equations in one variable.
- CCSS.Math.Content.8.EE.C.7
Solve linear equations in one variable.
- CCSS.Math.Content.6.EE.B
Reason about and solve one-variable equations and inequalities.
- CCSS.Math.Content.HSA-REI.B.3
Solve linear equations and inequalities in one variable, including equations with coefficients represented by letters.