Why $int^infty_01_>alphadalpha=|f(x)|$?Show that $int|f(x)|dx=int_0^infty m(E_alpha)dalpha$$e^-x^alpha$ is Lebesgue-integrable on $[0,infty)$ for $alpha>0$Show that the characteristic function of $mathbbQ$ is Lebesgue integrable.Lebesgue integral of f over R is bigger or equal to alpha times measure of $E_alpha?$$int_mathbbR^n frac1(lVert x-y rVert)^n- alpha dmu (y) = (n-alpha)int _[0,+infty[ r^alpha - n -1 mu(B(x,r)) dlambda (r)$For what $alpha > 0$ do we have $int_D_alpha f dlambda < + infty$ ?Show that $intlimits_[a,b]fdlambda = intlimits_(a,b) fdlambda$, for $-infty<a,b<infty$.Show that a differentiable function $f$, where $f(x)$ and $f'(x)$ are integrable, has a value of $0$ when Lebesgue integrated over the real numbers.DMCT $int fdmu=lim_ntoinfty int f_n dmu$ equivalent to $lim_ntoinftyint mid f_n -f mid dmu=0$?Show that $alpha f + beta g$ is measurable when $f,g$ are measurable.

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Why $int^infty_01_dalpha=|f(x)|$?


Show that $int|f(x)|dx=int_0^infty m(E_alpha)dalpha$$e^-x^alpha$ is Lebesgue-integrable on $[0,infty)$ for $alpha>0$Show that the characteristic function of $mathbbQ$ is Lebesgue integrable.Lebesgue integral of f over R is bigger or equal to alpha times measure of $E_alpha?$$int_mathbbR^n frac1(lVert x-y rVert)^n- alpha dmu (y) = (n-alpha)int _[0,+infty[ r^alpha - n -1 mu(B(x,r)) dlambda (r)$For what $alpha > 0$ do we have $int_D_alpha f dlambda < + infty$ ?Show that $intlimits_[a,b]fdlambda = intlimits_(a,b) fdlambda$, for $-infty<a,b<infty$.Show that a differentiable function $f$, where $f(x)$ and $f'(x)$ are integrable, has a value of $0$ when Lebesgue integrated over the real numbers.DMCT $int fdmu=lim_ntoinfty int f_n dmu$ equivalent to $lim_ntoinftyint mid f_n -f mid dmu=0$?Show that $alpha f + beta g$ is measurable when $f,g$ are measurable.













0












$begingroup$



$f$ is integrable on $mathbbR^d$. For each $alpha>0$, let $E_alpha=>alpha$. Show that
$$int_mathbbR^d|f(x)|dx=int^infty_0m(E_alpha)dalpha$$




I saw a proof of the above that uses the fact that
$$int^infty_01_dalpha=|f(x)|$$



Why is this true? Intuitively it seems like we're "stacking" the values of the characteristic function until we get to the value of $f$.



Any help is much appreciated










share|cite|improve this question









$endgroup$
















    0












    $begingroup$



    $f$ is integrable on $mathbbR^d$. For each $alpha>0$, let $E_alpha=>alpha$. Show that
    $$int_mathbbR^d|f(x)|dx=int^infty_0m(E_alpha)dalpha$$




    I saw a proof of the above that uses the fact that
    $$int^infty_01_dalpha=|f(x)|$$



    Why is this true? Intuitively it seems like we're "stacking" the values of the characteristic function until we get to the value of $f$.



    Any help is much appreciated










    share|cite|improve this question









    $endgroup$














      0












      0








      0





      $begingroup$



      $f$ is integrable on $mathbbR^d$. For each $alpha>0$, let $E_alpha=>alpha$. Show that
      $$int_mathbbR^d|f(x)|dx=int^infty_0m(E_alpha)dalpha$$




      I saw a proof of the above that uses the fact that
      $$int^infty_01_dalpha=|f(x)|$$



      Why is this true? Intuitively it seems like we're "stacking" the values of the characteristic function until we get to the value of $f$.



      Any help is much appreciated










      share|cite|improve this question









      $endgroup$





      $f$ is integrable on $mathbbR^d$. For each $alpha>0$, let $E_alpha=>alpha$. Show that
      $$int_mathbbR^d|f(x)|dx=int^infty_0m(E_alpha)dalpha$$




      I saw a proof of the above that uses the fact that
      $$int^infty_01_dalpha=|f(x)|$$



      Why is this true? Intuitively it seems like we're "stacking" the values of the characteristic function until we get to the value of $f$.



      Any help is much appreciated







      measure-theory proof-explanation lebesgue-integral






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Mar 13 at 10:07









      Joe Man AnalysisJoe Man Analysis

      56419




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          $begingroup$

          $1_>alpha $ is nothing but the charateristic function of the interval $(0,|f(x)|)$ so its integral equals the measure of this interval.






          share|cite|improve this answer









          $endgroup$












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            $begingroup$

            $1_>alpha $ is nothing but the charateristic function of the interval $(0,|f(x)|)$ so its integral equals the measure of this interval.






            share|cite|improve this answer









            $endgroup$

















              1












              $begingroup$

              $1_>alpha $ is nothing but the charateristic function of the interval $(0,|f(x)|)$ so its integral equals the measure of this interval.






              share|cite|improve this answer









              $endgroup$















                1












                1








                1





                $begingroup$

                $1_>alpha $ is nothing but the charateristic function of the interval $(0,|f(x)|)$ so its integral equals the measure of this interval.






                share|cite|improve this answer









                $endgroup$



                $1_>alpha $ is nothing but the charateristic function of the interval $(0,|f(x)|)$ so its integral equals the measure of this interval.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Mar 13 at 10:10









                Kavi Rama MurthyKavi Rama Murthy

                68.1k53068




                68.1k53068



























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