What is proof by contradiction?

• A proof by contradiction assumes the?opposite?result is true
• Then, through a series of logical steps, shows that this cannot be so

How do I do proof by contradiction?

• This type of proof often involves explanation in words alongside mathematical statements
• Start with a statement assuming the opposite is true
  • e.g. 'Assume...'

• Use?prime?factorisation?to write a?composite number?as a product of primes