Use proof by contradiction to show that there exist no integers x x\,x and y y\,y for which 4x+8y=54x + 8y = 54x+8y=5.
132 exam-style questions on OCR (MEI) A Level Maths 1.1 Proof, covering 1.1.1 Structure of mathematical proof, 1.1.2 Disproof by counter example, 1.1.3 Proof by contradiction (A-level only), and 1.1 Proof. Each one has a worked solution and a mark scheme showing where the marks go.