Write (2n+3)2−(2n−3)2(2n + 3)^2 - (2n - 3)^2(2n+3)2−(2n−3)2 in the form 12k12k12k, where k k\,k is an integer, for all positive integer values of nnn.
207 exam-style questions on OCR GCSE Maths Proof. Each one has a worked solution and a mark scheme showing where the marks go.