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1.4 A: Proof

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Question 47

Leo wishes to use proof by contradiction to prove the following statement:

'The sum of a rational number and an irrational number is always irrational.'

Identify the correct starting assumption for Leo's proof.

  • The sum of every rational number and every irrational number is irrational.
  • The sum of every rational number and every irrational number is rational.
  • There exists a rational number and an irrational number whose sum is rational.
  • There exists a rational number and an irrational number whose sum is irrational.
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1.4 A: Proof Questions

  1. A Level
  2. /Maths
  3. /1.4 A: Proof

Practise AQA A Level Maths 1.4 A: Proof with exam-style questions for A Level Maths. 107 questions covering 1.4.1 Structure and methods of proof, matched to the AQA A Level Maths (7357) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

Question bank