Given that n∈Nn \in \mathbb{N}n∈N, use algebra to prove by contradiction that
“if n2+6n+3 is even, then n is odd” \text{“if } n^2 + 6n + 3 \text{ is even, then } n \text{ is odd”} “if n2+6n+3 is even, then n is odd”107 exam-style questions on AQA A Level Maths 1.4.1 Structure and methods of proof. Each one has a worked solution and a mark scheme showing where the marks go.