Determine whether the set G is a groupunder the operation *

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SUMMARY

The set G, defined as G={c+di ∈ C | cd=0 and c+d≠0}, is analyzed for group properties under the operation of multiplication. The discussion confirms that the operation is closed within G, as demonstrated by the multiplication of two elements a=c+di and b=e+fi resulting in a product that remains in G. However, further proof is required to establish that the product satisfies the conditions of having either ac-bd=0 or ad+bc=0, but not both, to confirm G as a group.

PREREQUISITES
  • Understanding of complex numbers and their properties
  • Familiarity with group theory concepts such as closure, associativity, identity, and inverses
  • Knowledge of multiplication of complex numbers
  • Ability to manipulate algebraic expressions involving complex numbers
NEXT STEPS
  • Prove that the set G is closed under multiplication by verifying the conditions for all elements in G
  • Explore the concept of identity and inverse elements in the context of complex numbers
  • Study group theory to understand the implications of associativity in G
  • Investigate examples of other sets of complex numbers that form groups under different operations
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Mathematics students, particularly those studying abstract algebra and group theory, as well as educators looking to deepen their understanding of complex number operations and group properties.

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Homework Statement



G={c+di e C| cd =0 and c+d does not =0} a*b=ab

Homework Equations



OK, I know I need to prove closed under *, and associativity and identity and inverse. I was able to do it for other set, but I do not understand what this set is saying



The Attempt at a Solution



OK 1, a=c+di and b=e+fi then a*b = (c+di)(e+fi) =ce-de+edi+cfi = ce-de+(ed+cf)i which is in G so yes

Is that correct?
 
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But I also need to prove then that (ce-df)(ed+ce)=0?
 
It's not clear to me what you are asking. This is hte set of complex numbers a+ bi such that a or[/b\] b but not both are 0. Yes, (a+bi)*(c+ di)= (ac- bd)+ (ad+ bc)i. But you haven't shown that is in the set until you have shown that either ac- bd= 0 or ad+ bc= 0 but not both.
 

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