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If the group is simple, sylow is enough, otherwise i have no idea.

Kai
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1 Answers1

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I think you still use Sylow theory, except that there are two cases.

Let $G$ be a group of order 168. The number $n_7$ of Sylow 7-subgroups of $G$ must equal $1$ or $8$. If $n _7 = 1$, then there's a unique element of order 7. If $n_7 = 8$, there there are $8 \cdot 6 = 48$ elements of order 7.

manthanomen
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