Proof by Deduction (Edexcel IAL Maths)

Spec point — 1.1

Proof by deduction

What is proof by deduction?

Proof by deduction is when a mathematical and logical argument is used to show whether or not a result is true

How do I use proof by deduction?

You may also need to:

• Write multiples of n in the form kn for some integer k
• Use algebraic techniques, showing logical steps of simplifying
• Use correct mathematical notation

Sets of numbers

• ℕ - the set of natural numbers
• ℤ - the set of integers
• ℚ - the set of quotients/rational numbers
• ℝ - the set of real numbers

Exam Hint

• Try the result you are proving with a few values

  • Use a sequence of them (eg 1, 2, 3)
  • Try different types of numbers (positive, negative, zero)

• This may help you see a pattern and spot what is going on

Worked Example