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Question Number 192077 by Mastermind last updated on 07/May/23

Let H be a non−empty subset of  a group G, prove that the follow−  ing are equivalent  1) H is a subgroup of G  2) for a,b ∈ H, ab^(−1)  ∈ H  3) for a,b ∈ ab ∈ H  4) for a ∈ H, a^(−1)  ∈ H    Hint: prove 1)→2)→3)→4)→1)    Help!!!

LetHbeanonemptysubsetofagroupG,provethatthefollowingareequivalent1)HisasubgroupofG2)fora,bH,ab1H3)fora,babH4)foraH,a1HHint:prove1)2)3)4)1)Help!!!

Answered by deleteduser1 last updated on 07/May/23

H is a subgroup of G⇒H is a group with elements  from G.  ⇒ab∈H for a,b∈H  Since b∈H,b^(−1) ∈H  Hence,since a, b^(−1)  ∈H, ab^(−1) ∈H    ⇒ 1)⇒3)⇒2)⇒4)

HisasubgroupofGHisagroupwithelementsfromG.abHfora,bHSincebH,b1HHence,sincea,b1H,ab1H1)3)2)4)

Commented by Mastermind last updated on 07/May/23

Thank you so much sir

Thankyousomuchsir

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