How would one prove that if h is in H, then also h^-1, that is its inverse of it is also in H, if Z is only positive integers.(adsbygoogle = window.adsbygoogle || []).push({});

Where [tex]H=\{a^n: n\in Z^+\}[/tex] a in G

I managed to show, as stated that [tex] e=a^{m-n}\in H[/tex]

since i supposed that the group G is finite, and i also know that now i have to take two elements in H, say h and h' and then use the property that H is closed, and [tex]hh'=...=e\in H[/tex]

, but i cannot figure out how to pick up h and h'?

Can u help me on this?

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# Need help! Inverse!

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