x x\,x is an integer. Prove algebraically that the sum of x(x+5)x(x + 5)x(x+5) and x+9x + 9x+9 is always a square number.
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.