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4MA1/2F Jan 2020, Question 7: Inverse Functions

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 2F (Foundation) · Calculator · 4 marks

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The question, in short

Complete three number machines by filling in missing outputs, inputs or operations so each machine works correctly.

Summarised in our own words. Use the official paper for the exact wording and the diagram.

Part (a) · 1 mark

Find the output when input 10 goes through + 5 then × 4.

  1. 110 + 5 = 15
  2. 215 × 4 = 60

Answer60

Part (b) · 2 marks

Find the input that gives output 3 after − 2 then ÷ 6.

  1. 1Work backwards using inverse operations.
  2. 2Undo ÷ 6: 3 × 6 = 18
  3. 3Undo − 2: 18 + 2 = 20

Answer20

Part (c) · 1 mark

Find the missing operation so input 15 gives output 8 after ÷ 3.

  1. 115 ÷ 3 = 5
  2. 25 + 3 = 8

Answer+3

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