Doubt about proof the smallest subfield that contains a ring












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Proposition. Let $F$ a field and $Rne{0}$ a subring such that $1_Fin R$. We place $$F'=bigg{ab^{-1};|;ain R, bin Rsetminus{{0}}bigg},$$
the $F'$ is the smalles subfield of $F$ which contains $R$.




The I did not understand just one thing in the proof: because if $1_Fin R$, then $Rsubseteq F'$. Would anyone be kind enough to explain it?



Thanks!










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  • 1




    The ring must be much more than just that: it must be an integral domain...And you also must define the operations in that $;F';$ that you defined.
    – DonAntonio
    Nov 20 '18 at 17:54
















0















Proposition. Let $F$ a field and $Rne{0}$ a subring such that $1_Fin R$. We place $$F'=bigg{ab^{-1};|;ain R, bin Rsetminus{{0}}bigg},$$
the $F'$ is the smalles subfield of $F$ which contains $R$.




The I did not understand just one thing in the proof: because if $1_Fin R$, then $Rsubseteq F'$. Would anyone be kind enough to explain it?



Thanks!










share|cite|improve this question


















  • 1




    The ring must be much more than just that: it must be an integral domain...And you also must define the operations in that $;F';$ that you defined.
    – DonAntonio
    Nov 20 '18 at 17:54














0












0








0








Proposition. Let $F$ a field and $Rne{0}$ a subring such that $1_Fin R$. We place $$F'=bigg{ab^{-1};|;ain R, bin Rsetminus{{0}}bigg},$$
the $F'$ is the smalles subfield of $F$ which contains $R$.




The I did not understand just one thing in the proof: because if $1_Fin R$, then $Rsubseteq F'$. Would anyone be kind enough to explain it?



Thanks!










share|cite|improve this question














Proposition. Let $F$ a field and $Rne{0}$ a subring such that $1_Fin R$. We place $$F'=bigg{ab^{-1};|;ain R, bin Rsetminus{{0}}bigg},$$
the $F'$ is the smalles subfield of $F$ which contains $R$.




The I did not understand just one thing in the proof: because if $1_Fin R$, then $Rsubseteq F'$. Would anyone be kind enough to explain it?



Thanks!







abstract-algebra proof-verification






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asked Nov 20 '18 at 17:26









Jack J.

4421419




4421419








  • 1




    The ring must be much more than just that: it must be an integral domain...And you also must define the operations in that $;F';$ that you defined.
    – DonAntonio
    Nov 20 '18 at 17:54














  • 1




    The ring must be much more than just that: it must be an integral domain...And you also must define the operations in that $;F';$ that you defined.
    – DonAntonio
    Nov 20 '18 at 17:54








1




1




The ring must be much more than just that: it must be an integral domain...And you also must define the operations in that $;F';$ that you defined.
– DonAntonio
Nov 20 '18 at 17:54




The ring must be much more than just that: it must be an integral domain...And you also must define the operations in that $;F';$ that you defined.
– DonAntonio
Nov 20 '18 at 17:54










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Take any $ain R$ and $b=1_F$. Then $a=ab^{-1}in F'$. Hence $Rsubseteq F'$.






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    Take any $ain R$ and $b=1_F$. Then $a=ab^{-1}in F'$. Hence $Rsubseteq F'$.






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      Take any $ain R$ and $b=1_F$. Then $a=ab^{-1}in F'$. Hence $Rsubseteq F'$.






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        Take any $ain R$ and $b=1_F$. Then $a=ab^{-1}in F'$. Hence $Rsubseteq F'$.






        share|cite|improve this answer












        Take any $ain R$ and $b=1_F$. Then $a=ab^{-1}in F'$. Hence $Rsubseteq F'$.







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        answered Nov 20 '18 at 17:28









        user1551

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