Is it guaranteed that $sqrt[3]{a+sqrt{b}}$ can be denested with or without complex numbers?












2












$begingroup$


I tried to use the cubic formula before, but was always stuck at simplifying the cube root. I had learned that you can always simplify $sqrt{a+sqrt{b}}$ by solving, but can I always simplify $sqrt[3]{a+sqrt{b}}$, too, or is there a restriction?
Edit:
It can contain complex numbers, and I mean denesting by simplifying. $sqrt{a+sqrt{b}}$ is the same as solving m+n=a, and $mn={bover4}$.
Second Edit:

An example will be denesting $sqrt{1+sqrt{2}}$. $sqrt{1+sqrt{2}}$ will be $sqrt{m}+sqrt{n}$, where m+n=1, and $mn={1over2}$. Squaring the first equation then subtracting the second equation 4 times, m-n=$i$. So, $sqrt{1+sqrt{2}}$=$sqrt{1+iover2}+sqrt{1-iover2}$.










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  • $begingroup$
    I feel a bit confused about what you mean by "complex numbers". So can you please show perhaps an example of an acceptable denesting of $sqrt{1+sqrt{2}}$?
    $endgroup$
    – Edward H.
    Feb 1 at 1:28
















2












$begingroup$


I tried to use the cubic formula before, but was always stuck at simplifying the cube root. I had learned that you can always simplify $sqrt{a+sqrt{b}}$ by solving, but can I always simplify $sqrt[3]{a+sqrt{b}}$, too, or is there a restriction?
Edit:
It can contain complex numbers, and I mean denesting by simplifying. $sqrt{a+sqrt{b}}$ is the same as solving m+n=a, and $mn={bover4}$.
Second Edit:

An example will be denesting $sqrt{1+sqrt{2}}$. $sqrt{1+sqrt{2}}$ will be $sqrt{m}+sqrt{n}$, where m+n=1, and $mn={1over2}$. Squaring the first equation then subtracting the second equation 4 times, m-n=$i$. So, $sqrt{1+sqrt{2}}$=$sqrt{1+iover2}+sqrt{1-iover2}$.










share|cite|improve this question











$endgroup$












  • $begingroup$
    I feel a bit confused about what you mean by "complex numbers". So can you please show perhaps an example of an acceptable denesting of $sqrt{1+sqrt{2}}$?
    $endgroup$
    – Edward H.
    Feb 1 at 1:28














2












2








2


1



$begingroup$


I tried to use the cubic formula before, but was always stuck at simplifying the cube root. I had learned that you can always simplify $sqrt{a+sqrt{b}}$ by solving, but can I always simplify $sqrt[3]{a+sqrt{b}}$, too, or is there a restriction?
Edit:
It can contain complex numbers, and I mean denesting by simplifying. $sqrt{a+sqrt{b}}$ is the same as solving m+n=a, and $mn={bover4}$.
Second Edit:

An example will be denesting $sqrt{1+sqrt{2}}$. $sqrt{1+sqrt{2}}$ will be $sqrt{m}+sqrt{n}$, where m+n=1, and $mn={1over2}$. Squaring the first equation then subtracting the second equation 4 times, m-n=$i$. So, $sqrt{1+sqrt{2}}$=$sqrt{1+iover2}+sqrt{1-iover2}$.










share|cite|improve this question











$endgroup$




I tried to use the cubic formula before, but was always stuck at simplifying the cube root. I had learned that you can always simplify $sqrt{a+sqrt{b}}$ by solving, but can I always simplify $sqrt[3]{a+sqrt{b}}$, too, or is there a restriction?
Edit:
It can contain complex numbers, and I mean denesting by simplifying. $sqrt{a+sqrt{b}}$ is the same as solving m+n=a, and $mn={bover4}$.
Second Edit:

An example will be denesting $sqrt{1+sqrt{2}}$. $sqrt{1+sqrt{2}}$ will be $sqrt{m}+sqrt{n}$, where m+n=1, and $mn={1over2}$. Squaring the first equation then subtracting the second equation 4 times, m-n=$i$. So, $sqrt{1+sqrt{2}}$=$sqrt{1+iover2}+sqrt{1-iover2}$.







radicals nested-radicals






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edited Feb 1 at 19:40







Math Lover

















asked Jan 31 at 0:31









Math LoverMath Lover

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17410












  • $begingroup$
    I feel a bit confused about what you mean by "complex numbers". So can you please show perhaps an example of an acceptable denesting of $sqrt{1+sqrt{2}}$?
    $endgroup$
    – Edward H.
    Feb 1 at 1:28


















  • $begingroup$
    I feel a bit confused about what you mean by "complex numbers". So can you please show perhaps an example of an acceptable denesting of $sqrt{1+sqrt{2}}$?
    $endgroup$
    – Edward H.
    Feb 1 at 1:28
















$begingroup$
I feel a bit confused about what you mean by "complex numbers". So can you please show perhaps an example of an acceptable denesting of $sqrt{1+sqrt{2}}$?
$endgroup$
– Edward H.
Feb 1 at 1:28




$begingroup$
I feel a bit confused about what you mean by "complex numbers". So can you please show perhaps an example of an acceptable denesting of $sqrt{1+sqrt{2}}$?
$endgroup$
– Edward H.
Feb 1 at 1:28










1 Answer
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$begingroup$

If you mean "can be simplified" as deleting of nested radicals then it's not always possible.



For example, for $sqrt{3-2sqrt2}$ we can do it, but for $sqrt{sqrt2-1}$ it's impossible.



For $sqrt[3]{5sqrt2-7}$ we can do it, but for $sqrt[3]{sqrt2-1}$ it's impossible.



For $sqrt[3]{sqrt[3]2-1}$ we can do it, but for $sqrt[3]{sqrt[3]2+1}$ it's impossible.






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    1 Answer
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    active

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    1 Answer
    1






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    active

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    4












    $begingroup$

    If you mean "can be simplified" as deleting of nested radicals then it's not always possible.



    For example, for $sqrt{3-2sqrt2}$ we can do it, but for $sqrt{sqrt2-1}$ it's impossible.



    For $sqrt[3]{5sqrt2-7}$ we can do it, but for $sqrt[3]{sqrt2-1}$ it's impossible.



    For $sqrt[3]{sqrt[3]2-1}$ we can do it, but for $sqrt[3]{sqrt[3]2+1}$ it's impossible.






    share|cite|improve this answer









    $endgroup$


















      4












      $begingroup$

      If you mean "can be simplified" as deleting of nested radicals then it's not always possible.



      For example, for $sqrt{3-2sqrt2}$ we can do it, but for $sqrt{sqrt2-1}$ it's impossible.



      For $sqrt[3]{5sqrt2-7}$ we can do it, but for $sqrt[3]{sqrt2-1}$ it's impossible.



      For $sqrt[3]{sqrt[3]2-1}$ we can do it, but for $sqrt[3]{sqrt[3]2+1}$ it's impossible.






      share|cite|improve this answer









      $endgroup$
















        4












        4








        4





        $begingroup$

        If you mean "can be simplified" as deleting of nested radicals then it's not always possible.



        For example, for $sqrt{3-2sqrt2}$ we can do it, but for $sqrt{sqrt2-1}$ it's impossible.



        For $sqrt[3]{5sqrt2-7}$ we can do it, but for $sqrt[3]{sqrt2-1}$ it's impossible.



        For $sqrt[3]{sqrt[3]2-1}$ we can do it, but for $sqrt[3]{sqrt[3]2+1}$ it's impossible.






        share|cite|improve this answer









        $endgroup$



        If you mean "can be simplified" as deleting of nested radicals then it's not always possible.



        For example, for $sqrt{3-2sqrt2}$ we can do it, but for $sqrt{sqrt2-1}$ it's impossible.



        For $sqrt[3]{5sqrt2-7}$ we can do it, but for $sqrt[3]{sqrt2-1}$ it's impossible.



        For $sqrt[3]{sqrt[3]2-1}$ we can do it, but for $sqrt[3]{sqrt[3]2+1}$ it's impossible.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 31 at 1:03









        Michael RozenbergMichael Rozenberg

        110k1896201




        110k1896201






























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