How to find 2 constants in a probability distribution function?












0












$begingroup$


image of a function



How to find a and c in this function? In the example they are using limits, but I don't exactly understand why and how.



The answer is: $a = -1, c = 0$










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$endgroup$

















    0












    $begingroup$


    image of a function



    How to find a and c in this function? In the example they are using limits, but I don't exactly understand why and how.



    The answer is: $a = -1, c = 0$










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      image of a function



      How to find a and c in this function? In the example they are using limits, but I don't exactly understand why and how.



      The answer is: $a = -1, c = 0$










      share|cite|improve this question











      $endgroup$




      image of a function



      How to find a and c in this function? In the example they are using limits, but I don't exactly understand why and how.



      The answer is: $a = -1, c = 0$







      probability statistics






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      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 30 at 1:39









      Graham Kemp

      87.6k43578




      87.6k43578










      asked Jan 30 at 0:23









      qwerfdqwerfd

      32




      32






















          1 Answer
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          When $x = 1$, the cumulative distribution must be continuous with value $1$, so $a cdot 1^2 + 2 cdot 1 + c = 1$. Also, at $x = 0$ the distribution must be continuous with value $0$, so $a cdot 0^2 + 2 cdot 0 + c = 0$. From the second equation, $c = 0$. Plugging into the first gives $a = -1$.



          Here's the function:



          enter image description here






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            So the value of x will always be the value of the function itself?
            $endgroup$
            – qwerfd
            Jan 30 at 1:41










          • $begingroup$
            Huhhh??? No of course not! That would mean that $f(x) = x$... a straight line.
            $endgroup$
            – David G. Stork
            Jan 30 at 1:54










          • $begingroup$
            I just realized what I've said. And I think I understood, what I wanted to ask in the first place, myself. Thanks for helping out
            $endgroup$
            – qwerfd
            Jan 30 at 2:07














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          1 Answer
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          1 Answer
          1






          active

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          active

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          active

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          0












          $begingroup$

          When $x = 1$, the cumulative distribution must be continuous with value $1$, so $a cdot 1^2 + 2 cdot 1 + c = 1$. Also, at $x = 0$ the distribution must be continuous with value $0$, so $a cdot 0^2 + 2 cdot 0 + c = 0$. From the second equation, $c = 0$. Plugging into the first gives $a = -1$.



          Here's the function:



          enter image description here






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            So the value of x will always be the value of the function itself?
            $endgroup$
            – qwerfd
            Jan 30 at 1:41










          • $begingroup$
            Huhhh??? No of course not! That would mean that $f(x) = x$... a straight line.
            $endgroup$
            – David G. Stork
            Jan 30 at 1:54










          • $begingroup$
            I just realized what I've said. And I think I understood, what I wanted to ask in the first place, myself. Thanks for helping out
            $endgroup$
            – qwerfd
            Jan 30 at 2:07


















          0












          $begingroup$

          When $x = 1$, the cumulative distribution must be continuous with value $1$, so $a cdot 1^2 + 2 cdot 1 + c = 1$. Also, at $x = 0$ the distribution must be continuous with value $0$, so $a cdot 0^2 + 2 cdot 0 + c = 0$. From the second equation, $c = 0$. Plugging into the first gives $a = -1$.



          Here's the function:



          enter image description here






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            So the value of x will always be the value of the function itself?
            $endgroup$
            – qwerfd
            Jan 30 at 1:41










          • $begingroup$
            Huhhh??? No of course not! That would mean that $f(x) = x$... a straight line.
            $endgroup$
            – David G. Stork
            Jan 30 at 1:54










          • $begingroup$
            I just realized what I've said. And I think I understood, what I wanted to ask in the first place, myself. Thanks for helping out
            $endgroup$
            – qwerfd
            Jan 30 at 2:07
















          0












          0








          0





          $begingroup$

          When $x = 1$, the cumulative distribution must be continuous with value $1$, so $a cdot 1^2 + 2 cdot 1 + c = 1$. Also, at $x = 0$ the distribution must be continuous with value $0$, so $a cdot 0^2 + 2 cdot 0 + c = 0$. From the second equation, $c = 0$. Plugging into the first gives $a = -1$.



          Here's the function:



          enter image description here






          share|cite|improve this answer











          $endgroup$



          When $x = 1$, the cumulative distribution must be continuous with value $1$, so $a cdot 1^2 + 2 cdot 1 + c = 1$. Also, at $x = 0$ the distribution must be continuous with value $0$, so $a cdot 0^2 + 2 cdot 0 + c = 0$. From the second equation, $c = 0$. Plugging into the first gives $a = -1$.



          Here's the function:



          enter image description here







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Jan 30 at 1:54

























          answered Jan 30 at 1:12









          David G. StorkDavid G. Stork

          11.6k41534




          11.6k41534












          • $begingroup$
            So the value of x will always be the value of the function itself?
            $endgroup$
            – qwerfd
            Jan 30 at 1:41










          • $begingroup$
            Huhhh??? No of course not! That would mean that $f(x) = x$... a straight line.
            $endgroup$
            – David G. Stork
            Jan 30 at 1:54










          • $begingroup$
            I just realized what I've said. And I think I understood, what I wanted to ask in the first place, myself. Thanks for helping out
            $endgroup$
            – qwerfd
            Jan 30 at 2:07




















          • $begingroup$
            So the value of x will always be the value of the function itself?
            $endgroup$
            – qwerfd
            Jan 30 at 1:41










          • $begingroup$
            Huhhh??? No of course not! That would mean that $f(x) = x$... a straight line.
            $endgroup$
            – David G. Stork
            Jan 30 at 1:54










          • $begingroup$
            I just realized what I've said. And I think I understood, what I wanted to ask in the first place, myself. Thanks for helping out
            $endgroup$
            – qwerfd
            Jan 30 at 2:07


















          $begingroup$
          So the value of x will always be the value of the function itself?
          $endgroup$
          – qwerfd
          Jan 30 at 1:41




          $begingroup$
          So the value of x will always be the value of the function itself?
          $endgroup$
          – qwerfd
          Jan 30 at 1:41












          $begingroup$
          Huhhh??? No of course not! That would mean that $f(x) = x$... a straight line.
          $endgroup$
          – David G. Stork
          Jan 30 at 1:54




          $begingroup$
          Huhhh??? No of course not! That would mean that $f(x) = x$... a straight line.
          $endgroup$
          – David G. Stork
          Jan 30 at 1:54












          $begingroup$
          I just realized what I've said. And I think I understood, what I wanted to ask in the first place, myself. Thanks for helping out
          $endgroup$
          – qwerfd
          Jan 30 at 2:07






          $begingroup$
          I just realized what I've said. And I think I understood, what I wanted to ask in the first place, myself. Thanks for helping out
          $endgroup$
          – qwerfd
          Jan 30 at 2:07




















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