Solving $int^{+ infty}_{- infty} exp(-x-e^{-x})dx= frac{1}{c}$











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I need to solve an equation.
$int^{+ infty}_{- infty} exp(-x-e^{-x})dx= frac{1}{c}$



I know that
$int^{+infty}_{-infty} exp(-x-e^{-x})dx= lim_{a rightarrow -infty} int^{0}_{a} exp(-x-e^{-x})dx + lim_{b {rightarrow infty}} int^{b}_{0} exp(-x-e^{-x})dx$



Can somebody explain step by step how to integrate $int lim_{a rightarrow -infty} int^{a}_{0} exp(-x-e^{-x})dx $
I used variable exchange method and I got
$lim_{a rightarrow -infty} (e-e^{-a})$.



Is it right? But how to solve this limit?










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  • Are you sure about your limit expansion? Should they not be $a rightarrow infty$ and $b rightarrow -infty$?
    – Easymode44
    Nov 19 at 11:30















up vote
1
down vote

favorite












I need to solve an equation.
$int^{+ infty}_{- infty} exp(-x-e^{-x})dx= frac{1}{c}$



I know that
$int^{+infty}_{-infty} exp(-x-e^{-x})dx= lim_{a rightarrow -infty} int^{0}_{a} exp(-x-e^{-x})dx + lim_{b {rightarrow infty}} int^{b}_{0} exp(-x-e^{-x})dx$



Can somebody explain step by step how to integrate $int lim_{a rightarrow -infty} int^{a}_{0} exp(-x-e^{-x})dx $
I used variable exchange method and I got
$lim_{a rightarrow -infty} (e-e^{-a})$.



Is it right? But how to solve this limit?










share|cite|improve this question
























  • Are you sure about your limit expansion? Should they not be $a rightarrow infty$ and $b rightarrow -infty$?
    – Easymode44
    Nov 19 at 11:30













up vote
1
down vote

favorite









up vote
1
down vote

favorite











I need to solve an equation.
$int^{+ infty}_{- infty} exp(-x-e^{-x})dx= frac{1}{c}$



I know that
$int^{+infty}_{-infty} exp(-x-e^{-x})dx= lim_{a rightarrow -infty} int^{0}_{a} exp(-x-e^{-x})dx + lim_{b {rightarrow infty}} int^{b}_{0} exp(-x-e^{-x})dx$



Can somebody explain step by step how to integrate $int lim_{a rightarrow -infty} int^{a}_{0} exp(-x-e^{-x})dx $
I used variable exchange method and I got
$lim_{a rightarrow -infty} (e-e^{-a})$.



Is it right? But how to solve this limit?










share|cite|improve this question















I need to solve an equation.
$int^{+ infty}_{- infty} exp(-x-e^{-x})dx= frac{1}{c}$



I know that
$int^{+infty}_{-infty} exp(-x-e^{-x})dx= lim_{a rightarrow -infty} int^{0}_{a} exp(-x-e^{-x})dx + lim_{b {rightarrow infty}} int^{b}_{0} exp(-x-e^{-x})dx$



Can somebody explain step by step how to integrate $int lim_{a rightarrow -infty} int^{a}_{0} exp(-x-e^{-x})dx $
I used variable exchange method and I got
$lim_{a rightarrow -infty} (e-e^{-a})$.



Is it right? But how to solve this limit?







probability integration limits






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edited Nov 19 at 11:47









amWhy

191k28223439




191k28223439










asked Nov 19 at 10:06









Atstovas

587




587












  • Are you sure about your limit expansion? Should they not be $a rightarrow infty$ and $b rightarrow -infty$?
    – Easymode44
    Nov 19 at 11:30


















  • Are you sure about your limit expansion? Should they not be $a rightarrow infty$ and $b rightarrow -infty$?
    – Easymode44
    Nov 19 at 11:30
















Are you sure about your limit expansion? Should they not be $a rightarrow infty$ and $b rightarrow -infty$?
– Easymode44
Nov 19 at 11:30




Are you sure about your limit expansion? Should they not be $a rightarrow infty$ and $b rightarrow -infty$?
– Easymode44
Nov 19 at 11:30










2 Answers
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6
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This isn't an integral equation---it's just doing an integral. Change variable $u=e^{-x}$, and you get 1.






share|cite|improve this answer




























    up vote
    1
    down vote













    we have:
    $$I=intexpleft(-x-e^{-x}right)dx$$
    $$=int e^{-x-e^{-x}}dx$$
    $u=e^{-x}$ so $dx=frac{du}{-e^{-x}}$
    $$I=-int e^{-u}du=e^{-u}+C=e^{-e^{-x}}+C$$
    now put in limits






    share|cite|improve this answer























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      2 Answers
      2






      active

      oldest

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      2 Answers
      2






      active

      oldest

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      active

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      active

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      up vote
      6
      down vote













      This isn't an integral equation---it's just doing an integral. Change variable $u=e^{-x}$, and you get 1.






      share|cite|improve this answer

























        up vote
        6
        down vote













        This isn't an integral equation---it's just doing an integral. Change variable $u=e^{-x}$, and you get 1.






        share|cite|improve this answer























          up vote
          6
          down vote










          up vote
          6
          down vote









          This isn't an integral equation---it's just doing an integral. Change variable $u=e^{-x}$, and you get 1.






          share|cite|improve this answer












          This isn't an integral equation---it's just doing an integral. Change variable $u=e^{-x}$, and you get 1.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 19 at 10:12









          Richard Martin

          1,63918




          1,63918






















              up vote
              1
              down vote













              we have:
              $$I=intexpleft(-x-e^{-x}right)dx$$
              $$=int e^{-x-e^{-x}}dx$$
              $u=e^{-x}$ so $dx=frac{du}{-e^{-x}}$
              $$I=-int e^{-u}du=e^{-u}+C=e^{-e^{-x}}+C$$
              now put in limits






              share|cite|improve this answer



























                up vote
                1
                down vote













                we have:
                $$I=intexpleft(-x-e^{-x}right)dx$$
                $$=int e^{-x-e^{-x}}dx$$
                $u=e^{-x}$ so $dx=frac{du}{-e^{-x}}$
                $$I=-int e^{-u}du=e^{-u}+C=e^{-e^{-x}}+C$$
                now put in limits






                share|cite|improve this answer

























                  up vote
                  1
                  down vote










                  up vote
                  1
                  down vote









                  we have:
                  $$I=intexpleft(-x-e^{-x}right)dx$$
                  $$=int e^{-x-e^{-x}}dx$$
                  $u=e^{-x}$ so $dx=frac{du}{-e^{-x}}$
                  $$I=-int e^{-u}du=e^{-u}+C=e^{-e^{-x}}+C$$
                  now put in limits






                  share|cite|improve this answer














                  we have:
                  $$I=intexpleft(-x-e^{-x}right)dx$$
                  $$=int e^{-x-e^{-x}}dx$$
                  $u=e^{-x}$ so $dx=frac{du}{-e^{-x}}$
                  $$I=-int e^{-u}du=e^{-u}+C=e^{-e^{-x}}+C$$
                  now put in limits







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited Nov 21 at 0:16









                  Batominovski

                  32.9k23192




                  32.9k23192










                  answered Nov 21 at 0:09









                  Henry Lee

                  1,682218




                  1,682218






























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