A student named Elena makes the claim that there is a finite set of prime numbers P={p1,p2,p3,…,pk}P = \{p_1, p_2, p_3, \dots, p_k\}P={p1,p2,p3,…,pk} where pk p_k\,pk is the largest prime. Use the method of proof by contradiction to show that Elena's claim is incorrect, and thus prove that there are infinitely many prime numbers.
281 exam-style questions on CCEA A Level Maths 3.1 Algebra and functions (A-level only), covering 3.1.1 Algebra and functions (A-level only), 3.1.2 Algebra and functions (A-level only), 3.1.3 Algebra and functions (A-level only), 3.1.4 Algebra and functions (A-level only), 3.1.5 Algebra and functions (A-level only), 3.1.6 Algebra and functions (A-level only), 3.1.7 Algebra and functions (A-level only), 3.1.8 Algebra and functions (A-level only), 3.1.9 Algebra and functions (A-level only), and 3.1 Algebra and functions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.