Proof by Contradiction | 25 Worked Examples | Edexcel A-Level Maths

25 progressive Edexcel A-Level (9MA0) proof questions with full mark-scheme style worked solutions.

What’s inside:
Easy: disproof by counter-example, and short direct proofs by deduction.
Medium: proof by contradiction for classic results such as the irrationality of root 2 and the infinitude of primes.
Hard: harder contradiction arguments, no-rational-root reasoning, and questions that combine more than one proof technique.

Every solution shows every step, with M1 (method), A1 (accuracy) and B1 (independent) marks annotated at exactly the point each would be awarded. Typeset in LaTeX for clean mathematical notation.

Ideal for: Year 13 students sitting Edexcel A-Level Mathematics (9MA0) Paper 1 / Paper 2 Pure, plus tutors and teachers building targeted practice. Print-friendly, hand straight to students.