A landscape architect is designing a square decorative plaza with an area of A A\,A square metres, where A=s2A = s^2A=s2 and the side length s s\,s is an integer. During a drainage calculation, it is found that A A\,A is a multiple of 5. Use the method of proof by contradiction to prove that s s\,s must also be a multiple of 5.
107 exam-style questions on Edexcel A Level Maths 1.1 Proof by Contradiction. Each one has a worked solution and a mark scheme showing where the marks go.