Math Is Fun Forum

limpfisch

Member

Registered: 2012-05-08

Posts: 11

help with group theory please.

let a,b be members of a group (G,*). Show that if (a*b) inverse = (a inverse)*(b inverse) then a*b = b*a

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: help with group theory please.

hi limpfisch

For simplification I'll leave out the * (say, multiply), use I for the identity and  -1 for an inverse

multiply both sides by ab

Now multiply both sides by ba

Bob

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