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4MA1/1FR Jun 2019, Question 10: Inverse Functions

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

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The question, in short

A number machine multiplies the input by 7 then subtracts 9; find outputs, reverse the process, and express the output in terms of y.

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

Part (a) · 1 mark

Find the output when the input is 8.

  1. 18 × 7 = 56
  2. 256 − 9 = 47

Answer47

Part (b) · 2 marks

Find the input that gives an output of 82.

  1. 182 + 9 = 91
  2. 291 ÷ 7 = 13

Answer13

Part (c) · 2 marks

Write the output as an expression in terms of y.

  1. 1y × 7 = 7y
  2. 27y − 9

Answer7y− 9

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