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Joint pdf - find C

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    The joint probability density function is:

    The C is a constant.

    The ranges are x<1, y<1, x+y>1

    They're supposed to be less than or equal to, greater than or equal to.

    I am trying to find what the constant C is.

    I know the method as I have done similar questions before but this one doesn't seem to be working out for me.

    My method: integrate Cexp(x)exp(y), first with respect to y in between 1-x and 1.

    This gives me Cexp(x)(exp(1) - exp(1-x)

    I find that odd already with the exp(1).

    Then integrating again with respect to x between 0 and 1, I get  C (exp(2) +1)

    As the joint pdf equals one, this then gives me  C = \frac{1}{exp(2)+1}

    Doesn't look right to me...

    Can someone please point out where I went wrong?
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    (Original post by Mathlete29)
    Agree with your limits.

    After integrating wrt y, I get e^{x+1}-e

    and then after integrating wrt x, I get  e^2-2e

    Edit: Both times C, of course.


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