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4MA1/2FR Jan 2019, Question 7: Functions as a Mapping

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 2FR (Foundation) · Calculator · 3 marks

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The question, in short

A number machine halves the input then adds 10. Find the output for an input of 8, and find the input that gives an output of 120.

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

Part (a) · 1 mark

Starting with 8, apply the halving and adding 10 steps to get the result.

  1. 18 ÷ 2 = 4
  2. 24 + 10 = 14

Answer14

Part (b) · 2 marks

Reverse the two operations to determine which starting value produces 120.

  1. 1Work backwards: undo + 10, then undo ÷ 2.
  2. 2120 − 10 = 110
  3. 3110 × 2 = 220

Answer220

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