TMUA-P2Y-PRF-004 — Paper P2 · Following proofs · Level 2

Options

1. A
   The proof is valid; line (2) correctly exhibits an odd number.
2. B
   Line (1) is wrong: odd integers cannot be written this way.
3. C
   Lines (1)-(2) are correct algebra, but line (3) mislabels the outcome: $2(j + k + 1)$ with integer $j + k + 1$ is even, not odd, so the proof as titled fails (it in fact proves the sum is even).
4. D
   Line (2) is unjustified because $j + k + 1$ need not be an integer.

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

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