TMUA-P2-PRF3-003 — Paper P2 · Proof by contradiction · Level 2

Options

1. A
   Assume $n^2$ is even and $n$ is even.
2. B
   Assume $n^2$ is odd and $n$ is odd.
3. C
   Assume $n^2$ is even and $n$ is odd; then $n = 2k+1$ gives $n^2$ odd, contradicting the hypothesis.
4. D
   Assume $n$ is odd; then $n^2$ is odd, so the claim is proved directly.
5. E
   Assume $n^2$ is odd and $n$ is even.

Letters only — the answer key is hidden. Work it out, then check the solution below.

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