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Course Library · Lesson 6 of 6
Life · Guided lesson

Choose and check a model

About 13 minutes · 3 reading + 10 practice and checks
Time includes reading, practice, and questions. Extra videos or further study are optional.
See this course’s project requirements

A checked algebra notebook that models four situations, solves equations and inequalities, and tests solutions against the original conditions.

Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.

What to include

  • Include four clearly defined quantity models with units.
  • Show balanced transformations and distribution in at least one model.
  • State a permitted inequality set and check its boundary.
  • Check each final value in its original relationship.
  • Add all six changed-case responses and explain one infeasible whole-number arrangement.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Method: applies the course-specific rules to the supplied cases with visible intermediate work.
  • Accuracy: results agree with the stated facts, units, boundaries and independent checks.
  • Reasoning: explains why the result follows and identifies a limitation or unresolved question.
  • Transfer: completes changed cases and revises the final project when a relevant assumption changes.
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Before you begin

The idea in everyday life

Original cases: A) 34 badges contain four labels and five equal teams. B) A shelf holds at most 34 badges with the same arrangement.

The idea

Model selection starts with the relationship, not the presence of numbers. Distinguish a total equation from a capacity inequality, then check algebraic solutions against the original units and context.

Follow along

Choose and check a model — worked practice

Model selection starts with the relationship, not the presence of numbers. Distinguish a total equation from a capacity inequality, then check algebraic solutions against the original units and context.

Original cases: A) 34 badges contain four labels and five equal teams. B) A shelf holds at most 34 badges with the same arrangement.

Case information

Paste at A1.

ARecordBGiven
Original caseOriginal cases: A) 34 badges contain four labels and five equal teams. B) A shelf holds at most 34 badges with the same arrangement.

Copy as plain text
  1. 1. 1. Model a fixed total

    Write and solve the equation for case A.

    You should see: 5x+4=34; x=6 badges per team.

  2. 2. 2. Model a limit

    Write the inequality for case B and its permitted whole-number set.

    You should see: 5x+4≤34; whole-number x can be 0 through 6.

  3. 3. 3. Test a changed arrangement

    Use six teams, four labels and the same fixed total.

    You should see: 6x+4=34; x=5 badges per team.

  4. 4. 4. Assemble the notebook

    Place variable definitions, transformations and original checks next to each model.

    You should see: The fixed total gives one value; the capacity permits several values.

Now change one thing

An exact total is 39 badges with four labels and five equal teams.

Your work

What to finish

A checked comparison of exact-total and capacity models.

Common mistake

Watch for this

Definitions make the model interpretable and checkable.

How can I tell I understand it?

Choose a new model from the stated relationship rather than rounding an infeasible solution.

Try 3 questions

Quick knowledge check

Answer all 3 questions. Get at least 2 right and the lesson completes automatically.

Not yet passed

You’ll get an explanation for each answer. Signed in? Your results save to your account.

1“No more than 48 seats, six reserved, three per group” is represented by which model?
2An exact total gives x=6.2 teams. What should be concluded?
3A notebook shows answers but no variable definitions. What should be added?
0 of 3 answeredApply the lesson to a short question, then review the explanation.
6
Finish this lesson

Pass the check. We’ll save the progress.

Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

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Sources and further reading

Explore the references behind this lesson.

OpenStax: linear-equation strategy
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

OpenStax: linear inequalities
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

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