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 October 21st, 2017, 08:36 AM #1 Senior Member   Joined: Jan 2016 From: Blackpool Posts: 103 Thanks: 2 Can Probability density functions take negative values? My question is: evaluate the pdf at fx(3) where fx(x)=(-2)/((1+x)^3) and compute value -1/32, can pdf's be negative or have i made a mistake in the previous question? Thanks!
 October 21st, 2017, 08:40 AM #2 Senior Member     Joined: Sep 2015 From: USA Posts: 2,404 Thanks: 1306 pdf's can't be negative anywhere in their support. you've made a mistake somewhere.
October 21st, 2017, 01:25 PM   #3
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 Originally Posted by Jaket1 My question is: evaluate the pdf at fx(3) where fx(x)=(-2)/((1+x)^3) and compute value -1/32, can pdf's be negative or have i made a mistake in the previous question? Thanks!
Your f(x) is impossible. The definition of a density function requires it to be non-negative for all x and integrate to 1.

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