Prove that (3n+1)2−(3n−1)2(3n + 1)^2 - (3n - 1)^2(3n+1)2−(3n−1)2 is always a multiple of 12, for all positive integer values of nnn.
Practise OCR GCSE Maths Proof with exam-style questions for Foundation and Higher tier. 56 questions, matched to the OCR GCSE Maths (J560) specification and written in the written papers style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.