Problem related to multiple integral












1












$begingroup$


$g : mathbb{R}^{3} to mathbb{R}^{3} $ be a function defined by $g(x,y,z) = (3y+4z, 2x-3z, x+3y).$



Also let $S = {(x,y,z)in mathbb{R}^{3}: 0leq x leq 1, 0leq y leq 1, 0leq zleq 1 }$



Now the question is




If $$intintint_{g(s)}(2x+y-2z)dxdydz = alphaintintint_{s}zdxdydz,$$ then $alpha = ?$




The way I was thinking was not taking me too far. I was thinking $(3y+4z,2x-3z,x+3y) =(u,v,w)$ and was considering the scenario to be a change of variables like scenario but it's fruitless.



Can anyone guide me ? Any suggestions will be highly appreciated. Thank you










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$endgroup$

















    1












    $begingroup$


    $g : mathbb{R}^{3} to mathbb{R}^{3} $ be a function defined by $g(x,y,z) = (3y+4z, 2x-3z, x+3y).$



    Also let $S = {(x,y,z)in mathbb{R}^{3}: 0leq x leq 1, 0leq y leq 1, 0leq zleq 1 }$



    Now the question is




    If $$intintint_{g(s)}(2x+y-2z)dxdydz = alphaintintint_{s}zdxdydz,$$ then $alpha = ?$




    The way I was thinking was not taking me too far. I was thinking $(3y+4z,2x-3z,x+3y) =(u,v,w)$ and was considering the scenario to be a change of variables like scenario but it's fruitless.



    Can anyone guide me ? Any suggestions will be highly appreciated. Thank you










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      $g : mathbb{R}^{3} to mathbb{R}^{3} $ be a function defined by $g(x,y,z) = (3y+4z, 2x-3z, x+3y).$



      Also let $S = {(x,y,z)in mathbb{R}^{3}: 0leq x leq 1, 0leq y leq 1, 0leq zleq 1 }$



      Now the question is




      If $$intintint_{g(s)}(2x+y-2z)dxdydz = alphaintintint_{s}zdxdydz,$$ then $alpha = ?$




      The way I was thinking was not taking me too far. I was thinking $(3y+4z,2x-3z,x+3y) =(u,v,w)$ and was considering the scenario to be a change of variables like scenario but it's fruitless.



      Can anyone guide me ? Any suggestions will be highly appreciated. Thank you










      share|cite|improve this question









      $endgroup$




      $g : mathbb{R}^{3} to mathbb{R}^{3} $ be a function defined by $g(x,y,z) = (3y+4z, 2x-3z, x+3y).$



      Also let $S = {(x,y,z)in mathbb{R}^{3}: 0leq x leq 1, 0leq y leq 1, 0leq zleq 1 }$



      Now the question is




      If $$intintint_{g(s)}(2x+y-2z)dxdydz = alphaintintint_{s}zdxdydz,$$ then $alpha = ?$




      The way I was thinking was not taking me too far. I was thinking $(3y+4z,2x-3z,x+3y) =(u,v,w)$ and was considering the scenario to be a change of variables like scenario but it's fruitless.



      Can anyone guide me ? Any suggestions will be highly appreciated. Thank you







      integration






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      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 28 at 8:33









      hiren_garaihiren_garai

      515417




      515417






















          1 Answer
          1






          active

          oldest

          votes


















          0












          $begingroup$

          Indeed, this is a nice change of variables problem. It's a bit confusing to use the same variables for both sides of the equation though.



          After setting $(3y+4z,2x−3z,x+3y)=(u,v,w)$, the left hand side of the equation should be written using these coordinates. It is then very easy to see :
          $ 2u + v -2w = 5z$. Do not forget to include the determinant of the transformation $g$ in your final answer.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            ah ! I see. O e thing, by equation you mean the integral one, right ?
            $endgroup$
            – hiren_garai
            Jan 28 at 9:06










          • $begingroup$
            Yes. The one that has triple integrals on both sides.
            $endgroup$
            – ayberk
            Jan 28 at 9:25










          • $begingroup$
            But then I would have to change the $dxdydz$ according to the settings.
            $endgroup$
            – hiren_garai
            Jan 28 at 9:30










          • $begingroup$
            Exactly, the left hand side should be: $int_{g(S)} (2u+v−2w) du dv dw $
            $endgroup$
            – ayberk
            Jan 28 at 11:11













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          1 Answer
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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          0












          $begingroup$

          Indeed, this is a nice change of variables problem. It's a bit confusing to use the same variables for both sides of the equation though.



          After setting $(3y+4z,2x−3z,x+3y)=(u,v,w)$, the left hand side of the equation should be written using these coordinates. It is then very easy to see :
          $ 2u + v -2w = 5z$. Do not forget to include the determinant of the transformation $g$ in your final answer.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            ah ! I see. O e thing, by equation you mean the integral one, right ?
            $endgroup$
            – hiren_garai
            Jan 28 at 9:06










          • $begingroup$
            Yes. The one that has triple integrals on both sides.
            $endgroup$
            – ayberk
            Jan 28 at 9:25










          • $begingroup$
            But then I would have to change the $dxdydz$ according to the settings.
            $endgroup$
            – hiren_garai
            Jan 28 at 9:30










          • $begingroup$
            Exactly, the left hand side should be: $int_{g(S)} (2u+v−2w) du dv dw $
            $endgroup$
            – ayberk
            Jan 28 at 11:11


















          0












          $begingroup$

          Indeed, this is a nice change of variables problem. It's a bit confusing to use the same variables for both sides of the equation though.



          After setting $(3y+4z,2x−3z,x+3y)=(u,v,w)$, the left hand side of the equation should be written using these coordinates. It is then very easy to see :
          $ 2u + v -2w = 5z$. Do not forget to include the determinant of the transformation $g$ in your final answer.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            ah ! I see. O e thing, by equation you mean the integral one, right ?
            $endgroup$
            – hiren_garai
            Jan 28 at 9:06










          • $begingroup$
            Yes. The one that has triple integrals on both sides.
            $endgroup$
            – ayberk
            Jan 28 at 9:25










          • $begingroup$
            But then I would have to change the $dxdydz$ according to the settings.
            $endgroup$
            – hiren_garai
            Jan 28 at 9:30










          • $begingroup$
            Exactly, the left hand side should be: $int_{g(S)} (2u+v−2w) du dv dw $
            $endgroup$
            – ayberk
            Jan 28 at 11:11
















          0












          0








          0





          $begingroup$

          Indeed, this is a nice change of variables problem. It's a bit confusing to use the same variables for both sides of the equation though.



          After setting $(3y+4z,2x−3z,x+3y)=(u,v,w)$, the left hand side of the equation should be written using these coordinates. It is then very easy to see :
          $ 2u + v -2w = 5z$. Do not forget to include the determinant of the transformation $g$ in your final answer.






          share|cite|improve this answer









          $endgroup$



          Indeed, this is a nice change of variables problem. It's a bit confusing to use the same variables for both sides of the equation though.



          After setting $(3y+4z,2x−3z,x+3y)=(u,v,w)$, the left hand side of the equation should be written using these coordinates. It is then very easy to see :
          $ 2u + v -2w = 5z$. Do not forget to include the determinant of the transformation $g$ in your final answer.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 28 at 9:00









          ayberkayberk

          33715




          33715












          • $begingroup$
            ah ! I see. O e thing, by equation you mean the integral one, right ?
            $endgroup$
            – hiren_garai
            Jan 28 at 9:06










          • $begingroup$
            Yes. The one that has triple integrals on both sides.
            $endgroup$
            – ayberk
            Jan 28 at 9:25










          • $begingroup$
            But then I would have to change the $dxdydz$ according to the settings.
            $endgroup$
            – hiren_garai
            Jan 28 at 9:30










          • $begingroup$
            Exactly, the left hand side should be: $int_{g(S)} (2u+v−2w) du dv dw $
            $endgroup$
            – ayberk
            Jan 28 at 11:11




















          • $begingroup$
            ah ! I see. O e thing, by equation you mean the integral one, right ?
            $endgroup$
            – hiren_garai
            Jan 28 at 9:06










          • $begingroup$
            Yes. The one that has triple integrals on both sides.
            $endgroup$
            – ayberk
            Jan 28 at 9:25










          • $begingroup$
            But then I would have to change the $dxdydz$ according to the settings.
            $endgroup$
            – hiren_garai
            Jan 28 at 9:30










          • $begingroup$
            Exactly, the left hand side should be: $int_{g(S)} (2u+v−2w) du dv dw $
            $endgroup$
            – ayberk
            Jan 28 at 11:11


















          $begingroup$
          ah ! I see. O e thing, by equation you mean the integral one, right ?
          $endgroup$
          – hiren_garai
          Jan 28 at 9:06




          $begingroup$
          ah ! I see. O e thing, by equation you mean the integral one, right ?
          $endgroup$
          – hiren_garai
          Jan 28 at 9:06












          $begingroup$
          Yes. The one that has triple integrals on both sides.
          $endgroup$
          – ayberk
          Jan 28 at 9:25




          $begingroup$
          Yes. The one that has triple integrals on both sides.
          $endgroup$
          – ayberk
          Jan 28 at 9:25












          $begingroup$
          But then I would have to change the $dxdydz$ according to the settings.
          $endgroup$
          – hiren_garai
          Jan 28 at 9:30




          $begingroup$
          But then I would have to change the $dxdydz$ according to the settings.
          $endgroup$
          – hiren_garai
          Jan 28 at 9:30












          $begingroup$
          Exactly, the left hand side should be: $int_{g(S)} (2u+v−2w) du dv dw $
          $endgroup$
          – ayberk
          Jan 28 at 11:11






          $begingroup$
          Exactly, the left hand side should be: $int_{g(S)} (2u+v−2w) du dv dw $
          $endgroup$
          – ayberk
          Jan 28 at 11:11




















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