Subring $R=left{frac{m}{2^a3^b}|min mathbb{Z},a,binmathbb{N}right}$












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Show that $R=left{frac{m}{2^a3^b}|min mathbb{Z},a,binmathbb{N}right}$ is a subring of $mathbb{Q}$. Show that $frac{1}{5}notin R$. Is $mathbb{Z}$ in $R$?



I have already shown, that the product, the sum and the difference of two Elements from $R$ are in $R$.










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    0














    Show that $R=left{frac{m}{2^a3^b}|min mathbb{Z},a,binmathbb{N}right}$ is a subring of $mathbb{Q}$. Show that $frac{1}{5}notin R$. Is $mathbb{Z}$ in $R$?



    I have already shown, that the product, the sum and the difference of two Elements from $R$ are in $R$.










    share|cite|improve this question



























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      0








      0







      Show that $R=left{frac{m}{2^a3^b}|min mathbb{Z},a,binmathbb{N}right}$ is a subring of $mathbb{Q}$. Show that $frac{1}{5}notin R$. Is $mathbb{Z}$ in $R$?



      I have already shown, that the product, the sum and the difference of two Elements from $R$ are in $R$.










      share|cite|improve this question















      Show that $R=left{frac{m}{2^a3^b}|min mathbb{Z},a,binmathbb{N}right}$ is a subring of $mathbb{Q}$. Show that $frac{1}{5}notin R$. Is $mathbb{Z}$ in $R$?



      I have already shown, that the product, the sum and the difference of two Elements from $R$ are in $R$.







      abstract-algebra ring-theory






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      edited Nov 21 '18 at 11:29









      Tianlalu

      3,09621038




      3,09621038










      asked Nov 21 '18 at 11:23









      Arjihad

      383111




      383111






















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          Hint:
          $$
          frac{1}{5}in R
          iff frac{1}{5}=frac{m}{2^a3^b}
          iff {2^a3^b}= {5m}
          $$






          share|cite|improve this answer





















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            1 Answer
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            1 Answer
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            Hint:
            $$
            frac{1}{5}in R
            iff frac{1}{5}=frac{m}{2^a3^b}
            iff {2^a3^b}= {5m}
            $$






            share|cite|improve this answer


























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              Hint:
              $$
              frac{1}{5}in R
              iff frac{1}{5}=frac{m}{2^a3^b}
              iff {2^a3^b}= {5m}
              $$






              share|cite|improve this answer
























                0












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                Hint:
                $$
                frac{1}{5}in R
                iff frac{1}{5}=frac{m}{2^a3^b}
                iff {2^a3^b}= {5m}
                $$






                share|cite|improve this answer












                Hint:
                $$
                frac{1}{5}in R
                iff frac{1}{5}=frac{m}{2^a3^b}
                iff {2^a3^b}= {5m}
                $$







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Nov 21 '18 at 11:31









                lhf

                163k10167387




                163k10167387






























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