Solutions to the equation $3m^2equiv 1pmodp$ where $p$ is some prime

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Here is my question:




Solve the equation $3m^2equiv 1pmodp$, where $p$ is some prime.




This seems to be closely related to quadratic residues. For example, if we were to solve $x^2equiv -1pmodp$, we can conclude that the equation has solutions if and only if $pequiv 1pmod4$, using the famous Euler's criterion,
$$left(frac-1pright)equiv (-1)^fracp-12pmodp.$$



However, since now the square is multiplied by $3$, I had no idea what to do. I tried multiplying the inverse of $3$ modulo $p$ (assume $pneq 3$), to get $m^2equiv 3^-1pmodp$ but I don't know if I did anything wrong or is this even the right path to go.



Can anyone help? Thanks in advance.







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    up vote
    0
    down vote

    favorite












    Here is my question:




    Solve the equation $3m^2equiv 1pmodp$, where $p$ is some prime.




    This seems to be closely related to quadratic residues. For example, if we were to solve $x^2equiv -1pmodp$, we can conclude that the equation has solutions if and only if $pequiv 1pmod4$, using the famous Euler's criterion,
    $$left(frac-1pright)equiv (-1)^fracp-12pmodp.$$



    However, since now the square is multiplied by $3$, I had no idea what to do. I tried multiplying the inverse of $3$ modulo $p$ (assume $pneq 3$), to get $m^2equiv 3^-1pmodp$ but I don't know if I did anything wrong or is this even the right path to go.



    Can anyone help? Thanks in advance.







    share|cite|improve this question






















      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Here is my question:




      Solve the equation $3m^2equiv 1pmodp$, where $p$ is some prime.




      This seems to be closely related to quadratic residues. For example, if we were to solve $x^2equiv -1pmodp$, we can conclude that the equation has solutions if and only if $pequiv 1pmod4$, using the famous Euler's criterion,
      $$left(frac-1pright)equiv (-1)^fracp-12pmodp.$$



      However, since now the square is multiplied by $3$, I had no idea what to do. I tried multiplying the inverse of $3$ modulo $p$ (assume $pneq 3$), to get $m^2equiv 3^-1pmodp$ but I don't know if I did anything wrong or is this even the right path to go.



      Can anyone help? Thanks in advance.







      share|cite|improve this question












      Here is my question:




      Solve the equation $3m^2equiv 1pmodp$, where $p$ is some prime.




      This seems to be closely related to quadratic residues. For example, if we were to solve $x^2equiv -1pmodp$, we can conclude that the equation has solutions if and only if $pequiv 1pmod4$, using the famous Euler's criterion,
      $$left(frac-1pright)equiv (-1)^fracp-12pmodp.$$



      However, since now the square is multiplied by $3$, I had no idea what to do. I tried multiplying the inverse of $3$ modulo $p$ (assume $pneq 3$), to get $m^2equiv 3^-1pmodp$ but I don't know if I did anything wrong or is this even the right path to go.



      Can anyone help? Thanks in advance.









      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Aug 15 at 6:48









      blastzit

      344110




      344110




















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          Multiply through by 3, getting $(3m)^2equiv3modp$.



          Then there are clearly only solutions if 3 is a quadratic residue. Suppose it is, and $3equiva^2$. Then $3mequivpma$.






          share|cite|improve this answer




















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            1 Answer
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            1 Answer
            1






            active

            oldest

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            active

            oldest

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            active

            oldest

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            up vote
            1
            down vote



            accepted










            Multiply through by 3, getting $(3m)^2equiv3modp$.



            Then there are clearly only solutions if 3 is a quadratic residue. Suppose it is, and $3equiva^2$. Then $3mequivpma$.






            share|cite|improve this answer
























              up vote
              1
              down vote



              accepted










              Multiply through by 3, getting $(3m)^2equiv3modp$.



              Then there are clearly only solutions if 3 is a quadratic residue. Suppose it is, and $3equiva^2$. Then $3mequivpma$.






              share|cite|improve this answer






















                up vote
                1
                down vote



                accepted







                up vote
                1
                down vote



                accepted






                Multiply through by 3, getting $(3m)^2equiv3modp$.



                Then there are clearly only solutions if 3 is a quadratic residue. Suppose it is, and $3equiva^2$. Then $3mequivpma$.






                share|cite|improve this answer












                Multiply through by 3, getting $(3m)^2equiv3modp$.



                Then there are clearly only solutions if 3 is a quadratic residue. Suppose it is, and $3equiva^2$. Then $3mequivpma$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Aug 15 at 7:30









                Benedict Randall Shaw

                3139




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