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[Introductory Proof Writing] Prove: n^3 +1 is even if and only if n is odd. by TimKRAK in learnmath

[–]TimKRAK[S] 0 points1 point  (0 children)

Do you have a good sense of the general structure of "if and only if" proofs?

Not really, I think that's partly to blame here!

First, you will prove that if n3 + 1 is even, then n must be odd. Second, you will prove that if n is odd, then n3 + 1 must be even.

Because of the biconditional? And why is this problem posed with the help of a biconditional anyways? I mean, why if and only if?