1.2 Proof by exhaustion

AQA Edexcel OCR A OCR B (MEI)
Another method of proof is proof by exhaustion, where you test all possible cases to see if the statement you want to prove is true for all cases.

All cases must be true for this method to work. This method is suited for questions where there is a small number of cases to test.
Important
Proof by exhaustion involves:

  • List all the cases that exhausts all possibilities.
  • Show that the statement is true for each individual case.
Example 1.2.1
Prove that no square number can have a last digit of 2, 3, 7 or 8.
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