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## Main Question or Discussion Point

No. This isn't homework. And I think I am right there with this one.

I'm interested in the intersection of groups and what they equal, my professor proposed starting with something like this:

Show that if H and K are normal subgroups of a group G such that H∩K = {e}, then hk = kh for all h ∈ H and for all k ∈ K.

I've gotten this far:

kh

Am I allowed to assume what I just did?

I'm interested in the intersection of groups and what they equal, my professor proposed starting with something like this:

Show that if H and K are normal subgroups of a group G such that H∩K = {e}, then hk = kh for all h ∈ H and for all k ∈ K.

I've gotten this far:

kh

^{-1}k^{-1}= h(kh^{-1}k^{-1}) = (hkh^{-1})k^{-1}∈ H∩KAm I allowed to assume what I just did?

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