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4MA1/1FR Jun 2018, Question 6: Functions as a Mapping

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1FR (Foundation) · Calculator · 5 marks

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The question, in short

Apply two number machines: one multiplies by 4 then subtracts 8, the other multiplies by 5 then adds x; find outputs, inputs and the value of x.

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

Part (a) · 1 mark

Find the output of the ×4 then −8 machine when the input is 18.

  1. 118 × 4 = 72
  2. 272 − 8 = 64

Answer64

Part (b) · 2 marks

Find the input that gives output 20 for the ×4 then −8 machine.

  1. 1Work backwards through the machine
  2. 220 + 8 = 28
  3. 328 ÷ 4 = 7

Answer7

Part (c) · 2 marks

Given input 8 gives output 50 for the ×5 then +x machine, find x.

  1. 18 × 5 = 40
  2. 250 − 40 = 10, so x = 10

Answer10

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