# Lemmas are lame

Assume $$a,k \in \mathbb{Z}^+$$ and $$k>1$$ , then what can you say about the statement below:

If $$a \ | \ k \ and \ a \ | \ (-k)$$ then $$a=1 \ or \ k$$ if $$k$$ is a prime number.

Try more of my original problems in this set.

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