I know that E(X^2) is the definite integral of x^2 * f(x).

But what if f(x) = (4/3)(x^-2) ? The answer in the texbook says it is [4x/3].

I'm so confused. Thanks in advance :)

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- Aug 26th 2006, 06:25 PMfreswoodfinding variance of truncus pdf
I know that E(X^2) is the definite integral of x^2 * f(x).

But what if f(x) = (4/3)(x^-2) ? The answer in the texbook says it is [4x/3].

I'm so confused. Thanks in advance :) - Aug 26th 2006, 10:39 PMCaptainBlackQuote:

Originally Posted by**freswood**

a statement about its domain, which in this case would probably be

(4/3, infty). Then as the integration "integrates out" the dependency on x,

what you report as the textbooks answer cannot be the answer to the

question you have posted.

RonL