Skip to content

Course home

1.1.4 Proof by contradiction (A-level only)

1.1.4 Proof by contradiction (A-level only)

EasyMediumHard
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192
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.
[4]
Markscheme

1.1.4 Proof by contradiction (A-level only) Questions

  1. A Level
  2. /Maths
  3. /1.1.4 Proof by contradiction (A-level only)

107 exam-style questions on OCR A Level Maths 1.1.4 Proof by contradiction (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

Question bank