We know that $(n-a)^2 = n^2 - 2an + a^2$. Comparing this with the given equation $n^2 - 8n + 17 = 0$, we can see that $a^2$ should be 16 (since $(-4)^2 = 16$) instead of 17. So, we subtract 1 from both sides to make the left side a perfect square:
$$n^2 - 8n + 16
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