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Equations and inequalities
Lesson 24 of 75
Challenge

Form equations

Objective. Translate geometric and contextual information into equations.

  1. 1. Learn
  2. 2. Worked example
  3. 3. Practice
  4. 4. Feedback
  5. 5. Continue

Learn: the key idea

Form equations develops a connected mathematical idea rather than an isolated trick. Preserve balance while solving and representing solution sets. Begin by representing the quantities or relationships, choose a rule that fits, justify each transformation, and finish by checking units, signs, scale and whether the answer is reasonable.

Worked example

Check x = 8 in 2x + 1. Give the value.

Check x = 8 in 2x + 1
Illustrated card showing Check x = 8 in 2x + 1
  1. 1Identify the known information, the unknown and any conditions.
  2. 2Choose a diagram, table, graph or algebraic representation that exposes the structure.
  3. 3Apply the relevant rule one justified step at a time, keeping exact values where useful.
  4. 4Check by substitution, inverse reasoning or estimation. The result is 17.

Answer: 17

Concept mastery

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Practice

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Common mistake. A common error in form equations is to copy a procedure without checking its conditions. Label the structure first and justify every sign, operation and unit.

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