Edexcel IGCSE Maths

Revision Notes

2.8.1 Proof/Reasoning - Algebraic

What is proof?

  • Proof is the process of showing something is true in every case, often by using algebra

Given an algebraic expression…

  1. Expand brackets
  2. Simplify (work with left-hand side only if = sign involved)
  3. Make sure you finish with the statement you are proving

Given just words…

  • This is a bit trickier but turning it into algebra is usually the best thing to do

4. Give things names (use as few letters as possible):

    • n is “any integer” (or m or k or…)
    • n + 1 is the integer after n (“consecutive”)
    • 2n is an even integer (2n + 2 is the next one)
    • 2m is a different even integer
    • 2n + 1 is an odd integer (and 2n + 3 is the next one)

5. Then go on as above (“Given an Algebraic Expression”)

Exam Tip

“A multiple of k” means it can be written as k(……) – ie. k × …

Worked Example

Proof & Reasoning Worked Example, downloadable IGCSE & GCSE Maths revision notes

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