give 5 other equivalent iterated triple integrals












2












$begingroup$


I am given the following integral:
$$int_0^2int_0^{y^3}int_0^{y^2}f(x,y,z) dzdxdy $$
I was successfully able to rewrite this in its dzdydx, dxdzdy, and dxdydz forms, but I'm having a hard time understanding the iterated triple integrals where dy is the inner integral.



The solution for dydzdx is as follows:
$$int_0^8int_0^{x^{2/3}}int_{x^{1/3}}^2f(x,y,z)dydzdx,+,int_0^8int_{x^{2/3}}^4int_{z^{1/2}}^2f(x,y,z)dydzdx $$



I don't understand why the integral was split. How do I figure out what this shape looks like in the zx plane in order to even know that it needed to be split?










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    2












    $begingroup$


    I am given the following integral:
    $$int_0^2int_0^{y^3}int_0^{y^2}f(x,y,z) dzdxdy $$
    I was successfully able to rewrite this in its dzdydx, dxdzdy, and dxdydz forms, but I'm having a hard time understanding the iterated triple integrals where dy is the inner integral.



    The solution for dydzdx is as follows:
    $$int_0^8int_0^{x^{2/3}}int_{x^{1/3}}^2f(x,y,z)dydzdx,+,int_0^8int_{x^{2/3}}^4int_{z^{1/2}}^2f(x,y,z)dydzdx $$



    I don't understand why the integral was split. How do I figure out what this shape looks like in the zx plane in order to even know that it needed to be split?










    share|cite|improve this question









    $endgroup$















      2












      2








      2


      1



      $begingroup$


      I am given the following integral:
      $$int_0^2int_0^{y^3}int_0^{y^2}f(x,y,z) dzdxdy $$
      I was successfully able to rewrite this in its dzdydx, dxdzdy, and dxdydz forms, but I'm having a hard time understanding the iterated triple integrals where dy is the inner integral.



      The solution for dydzdx is as follows:
      $$int_0^8int_0^{x^{2/3}}int_{x^{1/3}}^2f(x,y,z)dydzdx,+,int_0^8int_{x^{2/3}}^4int_{z^{1/2}}^2f(x,y,z)dydzdx $$



      I don't understand why the integral was split. How do I figure out what this shape looks like in the zx plane in order to even know that it needed to be split?










      share|cite|improve this question









      $endgroup$




      I am given the following integral:
      $$int_0^2int_0^{y^3}int_0^{y^2}f(x,y,z) dzdxdy $$
      I was successfully able to rewrite this in its dzdydx, dxdzdy, and dxdydz forms, but I'm having a hard time understanding the iterated triple integrals where dy is the inner integral.



      The solution for dydzdx is as follows:
      $$int_0^8int_0^{x^{2/3}}int_{x^{1/3}}^2f(x,y,z)dydzdx,+,int_0^8int_{x^{2/3}}^4int_{z^{1/2}}^2f(x,y,z)dydzdx $$



      I don't understand why the integral was split. How do I figure out what this shape looks like in the zx plane in order to even know that it needed to be split?







      calculus integration multivariable-calculus






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      asked Jan 28 at 23:49









      user10939145user10939145

      111




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          2 Answers
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          $begingroup$

          The conditions on $y$ are $y^{2} >z$ and $y^{3} >x$. We have to integrate w.r.t. $y$ from the maximum of $sqrt z$ and $x^{1/3}$ to $2$. In order to carry this out it is convenient to split the possible values of $x$ and $z$ into two parts: $x>z^{2/3}$ and $x<z^{2/3}$ so that we know what the maximum is. This is what they have done.






          share|cite|improve this answer









          $endgroup$





















            1












            $begingroup$

            The region of the integral is characterized by
            $$
            0 leq y leq 2
            \ 0 leq x leq y^3 \ 0 leq z leq y^2
            $$



            If we have in mind that $x$ should be the outermost variable, the first thing is to deduce that $$0 leq x leq y^3 leq 2^3 = 8 \ 0 leq z leq y^2 leq 4$$



            The $0 leq x leq 2^3 = 8$ part gives the outer integral limits.



            And we also have two lower-boundary conditions on $y$, namely
            $$ y geq x^{1/3} \ y geq z^{1/2}$$
            And here is why the integral has to be split up -- we have no clue whether $x^{1/3}$ is more or less than $z^{1/2}$. If it is greater or equal, then $zleq x^{2/3}$ and the limits will be
            $$
            int_{x=0}^8int_{z= 0}^{x^{2/3}} int_{y=x^{1/3}}^2
            $$

            and if $x^{1/3} < z^{1/2}$ the upper limit on $z$ is given by $z leq y^2 leq 4$ and the limits will be
            $$
            int_{x=0}^8int_{z= x^{2/3}}^{4} int_{y=z^{1/2}}^2
            $$






            share|cite|improve this answer









            $endgroup$














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              2 Answers
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              active

              oldest

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              2 Answers
              2






              active

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              active

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              active

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              1












              $begingroup$

              The conditions on $y$ are $y^{2} >z$ and $y^{3} >x$. We have to integrate w.r.t. $y$ from the maximum of $sqrt z$ and $x^{1/3}$ to $2$. In order to carry this out it is convenient to split the possible values of $x$ and $z$ into two parts: $x>z^{2/3}$ and $x<z^{2/3}$ so that we know what the maximum is. This is what they have done.






              share|cite|improve this answer









              $endgroup$


















                1












                $begingroup$

                The conditions on $y$ are $y^{2} >z$ and $y^{3} >x$. We have to integrate w.r.t. $y$ from the maximum of $sqrt z$ and $x^{1/3}$ to $2$. In order to carry this out it is convenient to split the possible values of $x$ and $z$ into two parts: $x>z^{2/3}$ and $x<z^{2/3}$ so that we know what the maximum is. This is what they have done.






                share|cite|improve this answer









                $endgroup$
















                  1












                  1








                  1





                  $begingroup$

                  The conditions on $y$ are $y^{2} >z$ and $y^{3} >x$. We have to integrate w.r.t. $y$ from the maximum of $sqrt z$ and $x^{1/3}$ to $2$. In order to carry this out it is convenient to split the possible values of $x$ and $z$ into two parts: $x>z^{2/3}$ and $x<z^{2/3}$ so that we know what the maximum is. This is what they have done.






                  share|cite|improve this answer









                  $endgroup$



                  The conditions on $y$ are $y^{2} >z$ and $y^{3} >x$. We have to integrate w.r.t. $y$ from the maximum of $sqrt z$ and $x^{1/3}$ to $2$. In order to carry this out it is convenient to split the possible values of $x$ and $z$ into two parts: $x>z^{2/3}$ and $x<z^{2/3}$ so that we know what the maximum is. This is what they have done.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jan 29 at 0:03









                  Kavi Rama MurthyKavi Rama Murthy

                  71.1k53170




                  71.1k53170























                      1












                      $begingroup$

                      The region of the integral is characterized by
                      $$
                      0 leq y leq 2
                      \ 0 leq x leq y^3 \ 0 leq z leq y^2
                      $$



                      If we have in mind that $x$ should be the outermost variable, the first thing is to deduce that $$0 leq x leq y^3 leq 2^3 = 8 \ 0 leq z leq y^2 leq 4$$



                      The $0 leq x leq 2^3 = 8$ part gives the outer integral limits.



                      And we also have two lower-boundary conditions on $y$, namely
                      $$ y geq x^{1/3} \ y geq z^{1/2}$$
                      And here is why the integral has to be split up -- we have no clue whether $x^{1/3}$ is more or less than $z^{1/2}$. If it is greater or equal, then $zleq x^{2/3}$ and the limits will be
                      $$
                      int_{x=0}^8int_{z= 0}^{x^{2/3}} int_{y=x^{1/3}}^2
                      $$

                      and if $x^{1/3} < z^{1/2}$ the upper limit on $z$ is given by $z leq y^2 leq 4$ and the limits will be
                      $$
                      int_{x=0}^8int_{z= x^{2/3}}^{4} int_{y=z^{1/2}}^2
                      $$






                      share|cite|improve this answer









                      $endgroup$


















                        1












                        $begingroup$

                        The region of the integral is characterized by
                        $$
                        0 leq y leq 2
                        \ 0 leq x leq y^3 \ 0 leq z leq y^2
                        $$



                        If we have in mind that $x$ should be the outermost variable, the first thing is to deduce that $$0 leq x leq y^3 leq 2^3 = 8 \ 0 leq z leq y^2 leq 4$$



                        The $0 leq x leq 2^3 = 8$ part gives the outer integral limits.



                        And we also have two lower-boundary conditions on $y$, namely
                        $$ y geq x^{1/3} \ y geq z^{1/2}$$
                        And here is why the integral has to be split up -- we have no clue whether $x^{1/3}$ is more or less than $z^{1/2}$. If it is greater or equal, then $zleq x^{2/3}$ and the limits will be
                        $$
                        int_{x=0}^8int_{z= 0}^{x^{2/3}} int_{y=x^{1/3}}^2
                        $$

                        and if $x^{1/3} < z^{1/2}$ the upper limit on $z$ is given by $z leq y^2 leq 4$ and the limits will be
                        $$
                        int_{x=0}^8int_{z= x^{2/3}}^{4} int_{y=z^{1/2}}^2
                        $$






                        share|cite|improve this answer









                        $endgroup$
















                          1












                          1








                          1





                          $begingroup$

                          The region of the integral is characterized by
                          $$
                          0 leq y leq 2
                          \ 0 leq x leq y^3 \ 0 leq z leq y^2
                          $$



                          If we have in mind that $x$ should be the outermost variable, the first thing is to deduce that $$0 leq x leq y^3 leq 2^3 = 8 \ 0 leq z leq y^2 leq 4$$



                          The $0 leq x leq 2^3 = 8$ part gives the outer integral limits.



                          And we also have two lower-boundary conditions on $y$, namely
                          $$ y geq x^{1/3} \ y geq z^{1/2}$$
                          And here is why the integral has to be split up -- we have no clue whether $x^{1/3}$ is more or less than $z^{1/2}$. If it is greater or equal, then $zleq x^{2/3}$ and the limits will be
                          $$
                          int_{x=0}^8int_{z= 0}^{x^{2/3}} int_{y=x^{1/3}}^2
                          $$

                          and if $x^{1/3} < z^{1/2}$ the upper limit on $z$ is given by $z leq y^2 leq 4$ and the limits will be
                          $$
                          int_{x=0}^8int_{z= x^{2/3}}^{4} int_{y=z^{1/2}}^2
                          $$






                          share|cite|improve this answer









                          $endgroup$



                          The region of the integral is characterized by
                          $$
                          0 leq y leq 2
                          \ 0 leq x leq y^3 \ 0 leq z leq y^2
                          $$



                          If we have in mind that $x$ should be the outermost variable, the first thing is to deduce that $$0 leq x leq y^3 leq 2^3 = 8 \ 0 leq z leq y^2 leq 4$$



                          The $0 leq x leq 2^3 = 8$ part gives the outer integral limits.



                          And we also have two lower-boundary conditions on $y$, namely
                          $$ y geq x^{1/3} \ y geq z^{1/2}$$
                          And here is why the integral has to be split up -- we have no clue whether $x^{1/3}$ is more or less than $z^{1/2}$. If it is greater or equal, then $zleq x^{2/3}$ and the limits will be
                          $$
                          int_{x=0}^8int_{z= 0}^{x^{2/3}} int_{y=x^{1/3}}^2
                          $$

                          and if $x^{1/3} < z^{1/2}$ the upper limit on $z$ is given by $z leq y^2 leq 4$ and the limits will be
                          $$
                          int_{x=0}^8int_{z= x^{2/3}}^{4} int_{y=z^{1/2}}^2
                          $$







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered Jan 29 at 0:22









                          Mark FischlerMark Fischler

                          33.8k12552




                          33.8k12552






























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