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Free Grade 3 Introducing Composite Functions Common Errors Lessons

Free Grade 3 lessons for Introducing Composite Functions Common Errors: 12 real questions with a full answer key and worked solutions. A function is a rule that turns an input into an output. The inverse function reverses it.

Price

Free

Difficulty

Foundation

Estimated time

15 min

Total marks

24

Learning objectives

Every objective is checkable, and each one maps to an activity and an assessment.

  • RememberIdentify introducing composite functions common errors

    Identify introducing composite functions common errors accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • UnderstandExplain introducing composite functions common errors

    Explain introducing composite functions common errors accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • ApplyCalculate introducing composite functions common errors

    Calculate introducing composite functions common errors accurately in a familiar context.

    Assessed by: Exit ticket of four short items

  • AnalyseCompare introducing composite functions common errors

    Compare introducing composite functions common errors accurately in a familiar context.

    Assessed by: Exit ticket of four short items

Prerequisites

Close these gaps first — each has its own free lesson, worksheet and quiz.

How Introducing Composite Functions Common Errors works

A function is a rule that turns an input into an output. The inverse function reverses it.

Key wordsfunctioninputoutputinverse

12 practice questions

Easy to hard, 24 marks in total. Try them first, then open the answers.

  1. 1.f(x) = 2x − 4. Find f(3).[1]
  2. 2.f(x) = 6x + 8. Find f(-2).[1]
  3. 3.f(x) = 3x − 6. Find f(1).[1]
  4. 4.f(x) = 3x − 7. Find f(1).[1]
  5. 5.f(x) = 6x − 4. Find f(-2).[2]
  6. 6.f(x) = 4x − 6. Find f(-1).[2]
  7. 7.f(x) = 3x − 7. Find f(4).[2]
  8. 8.f(x) = 5x − 2. Find f(3).[2]
  9. 9.f(x) = 3x − 3. Find the inverse f⁻¹(x).[3]
  10. 10.f(x) = 3x − 8. Find the inverse f⁻¹(x).[3]
  11. 11.f(x) = 2x − 4. Find the inverse f⁻¹(x).[3]
  12. 12.f(x) = 3x − 1. Find the inverse f⁻¹(x).[3]
Show answers and working
  1. 1. 2

    Replace x with 3: 2 × 3 − 4. = 2

  2. 2. -4

    Replace x with -2: 6 × (-2) + 8. = -4

  3. 3. -3

    Replace x with 1: 3 × 1 − 6. = -3

  4. 4. -4

    Replace x with 1: 3 × 1 − 7. = -4

  5. 5. -16

    Replace x with -2: 6 × (-2) − 4. = -16

  6. 6. -10

    Replace x with -1: 4 × (-1) − 6. = -10

  7. 7. 5

    Replace x with 4: 3 × 4 − 7. = 5

  8. 8. 13

    Replace x with 3: 5 × 3 − 2. = 13

  9. 9. f⁻¹(x) = (x + 3) / 3

    Write y = 3x − 3 and swap x and y. Rearrange for y: y = (x + 3) / 3.

  10. 10. f⁻¹(x) = (x + 8) / 3

    Write y = 3x − 8 and swap x and y. Rearrange for y: y = (x + 8) / 3.

  11. 11. f⁻¹(x) = (x + 4) / 2

    Write y = 2x − 4 and swap x and y. Rearrange for y: y = (x + 4) / 2.

  12. 12. f⁻¹(x) = (x + 1) / 3

    Write y = 3x − 1 and swap x and y. Rearrange for y: y = (x + 1) / 3.

Worked examples

Easy example

f(x) = 2x + 4. Find f(3).

  1. Replace x with 3: 2 × 3 + 4.
  2. = 10
  3. Answer: 10
Medium example

f(x) = 6x − 7. Find f(3).

  1. Replace x with 3: 6 × 3 − 7.
  2. = 11
  3. Answer: 11
Hard example

f(x) = 4x − 5. Find the inverse f⁻¹(x).

  1. Write y = 4x − 5 and swap x and y.
  2. Rearrange for y: y = (x + 5) / 4.
  3. Answer: f⁻¹(x) = (x + 5) / 4

Interactive practice

Free, no account required — answer on screen or print it.

Common mistakes

What learners typically get wrong, and how to fix it.

  • Reads f(3) as f × 3.

    Correction: f(3) means 'put 3 into the rule'.

  • Reverses operations in the wrong order for the inverse.

    Correction: Undo the last step first.

Teacher tips

  • · Use function machines before notation.

Parent tips

  • · Play 'guess my rule' with numbers.

Real-life applications

  • · Converting temperatures, phone-plan costs.

Assessment objectives

How mastery is evidenced, and which standards it maps to.

IB IB-519.1 — Mapped statement covering Introducing Composite Functions Common Errors.EDEXCEL EDE-916.2 — Mapped statement covering Introducing Composite Functions Common Errors.

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Frequently asked

Is this Grade 3 Introducing Composite Functions Common Errors lesson really free?
Yes. Every lessons on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
What should a learner already know before this?
Start with Introducing Composite Functions Word Problems, Introducing Composite Functions Techniques, Domain and Range. Each one has its own free lesson, worksheet and quiz.
How is the lesson sequenced?
Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
What comes next after Introducing Composite Functions Common Errors?
Move on to Working with Composite Functions, Composite Functions in Context, which build directly on this idea.

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