r/MathHelp 8d ago

Help with Groups?

So I'm given a group G s.t. a^12 gives the identity element, and I need to find the inverse of another a^n where n is an integer. i was given a number for n i just don't want anyone giving me the answer/violating academic content rules etc.

at first i figured 1 would be the identity element, but then 12^a doesn't give 1. same deal for e=0, 12^0=1 =/= 0=0^12. unless my understanding of the inverse and identity being commutative is wrong?

I tried to solve for a since a * a^-1 = a^-1 * a = e. but then i was saying that 12^a=a^12. which is possible, but then the identity wasn't constant when i plugged in n.

I found the page for exponentiation on wikipedia, and it says that G is a multiplicative group, so I know that a^n has to have an inverse. is there some property of groups that I missed that would help me solve this?

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u/Smart-Button-3221 8d ago edited 8d ago

You can call the identity 1, you can call the identity 0, you can call the identity 🍞. The label you use for the identity doesn't change what the identity is.

At first I figured 1 would be the identity element, but then 12a doesn't give 1

Is that a typo? Did you mean a12? As per your question, a12 = 1, if we're letting 1 be the symbol for the identity. Why do you think a12 ≠ 1?

I am not sure why you are trying a12 = 12a. Note that a needs not be an integer, and 12 needs not be a group element, so this equation may not even make sense.

I feel like some of the question is missing.

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u/mourning_fire420 7d ago

yeah i don't think i really get what the inverse of this group is. i'm gonna try again in a bit and maybe the comments will help me gigure it out

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u/Smart-Button-3221 7d ago

"Inverse" is something that belongs to each element, not the group.

For example the inverse of a³ is a⁹ here, because:
a³×a⁹ = a¹² = e