What is the Probability density function of $X^2$ where X is an Uniform distribution












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I'm a student and I'm studying random variables and very new to it. I was studying the Uniform distribution and in it, it calculates the Expected of $X^2$ by $$ Eleft(X^2right) = int_{- infty}^infty x^2 p(x) dx $$
I understand the calculation of it, but if the Probability density function plot of $X$ is like that (I fully understand that) I can't imagine the Probability density function of the $X^2$ because if we span the Probability density function of $X$ which is within $[a,b]$ to $[a^2,b^2]$ then the integral of $int_{a^2}^{b^2} p(sqrt x) dx$ may not be equal to 1 I guess.



Could you help me figure out what is the Probability density function of $X^2$?










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  • 1




    $begingroup$
    I actually computed the pdf of $X^2$ for a general random variable here: math.stackexchange.com/a/3043502/90543
    $endgroup$
    – jgon
    Dec 23 '18 at 17:21










  • $begingroup$
    @jgon thank you. it was hard for me to understand your answer because I'm very new to it, but finally, I get it. so I was right, it is not that simple that in the basic tutorials they just integral $int_{- infty}^infty x^2 p(x) d_x $ to find the Expected. nice answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 17:36
















1












$begingroup$


I'm a student and I'm studying random variables and very new to it. I was studying the Uniform distribution and in it, it calculates the Expected of $X^2$ by $$ Eleft(X^2right) = int_{- infty}^infty x^2 p(x) dx $$
I understand the calculation of it, but if the Probability density function plot of $X$ is like that (I fully understand that) I can't imagine the Probability density function of the $X^2$ because if we span the Probability density function of $X$ which is within $[a,b]$ to $[a^2,b^2]$ then the integral of $int_{a^2}^{b^2} p(sqrt x) dx$ may not be equal to 1 I guess.



Could you help me figure out what is the Probability density function of $X^2$?










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    I actually computed the pdf of $X^2$ for a general random variable here: math.stackexchange.com/a/3043502/90543
    $endgroup$
    – jgon
    Dec 23 '18 at 17:21










  • $begingroup$
    @jgon thank you. it was hard for me to understand your answer because I'm very new to it, but finally, I get it. so I was right, it is not that simple that in the basic tutorials they just integral $int_{- infty}^infty x^2 p(x) d_x $ to find the Expected. nice answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 17:36














1












1








1





$begingroup$


I'm a student and I'm studying random variables and very new to it. I was studying the Uniform distribution and in it, it calculates the Expected of $X^2$ by $$ Eleft(X^2right) = int_{- infty}^infty x^2 p(x) dx $$
I understand the calculation of it, but if the Probability density function plot of $X$ is like that (I fully understand that) I can't imagine the Probability density function of the $X^2$ because if we span the Probability density function of $X$ which is within $[a,b]$ to $[a^2,b^2]$ then the integral of $int_{a^2}^{b^2} p(sqrt x) dx$ may not be equal to 1 I guess.



Could you help me figure out what is the Probability density function of $X^2$?










share|cite|improve this question











$endgroup$




I'm a student and I'm studying random variables and very new to it. I was studying the Uniform distribution and in it, it calculates the Expected of $X^2$ by $$ Eleft(X^2right) = int_{- infty}^infty x^2 p(x) dx $$
I understand the calculation of it, but if the Probability density function plot of $X$ is like that (I fully understand that) I can't imagine the Probability density function of the $X^2$ because if we span the Probability density function of $X$ which is within $[a,b]$ to $[a^2,b^2]$ then the integral of $int_{a^2}^{b^2} p(sqrt x) dx$ may not be equal to 1 I guess.



Could you help me figure out what is the Probability density function of $X^2$?







random-variables uniform-distribution density-function expected-value






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 31 '18 at 21:15









Davide Giraudo

128k17156268




128k17156268










asked Dec 23 '18 at 17:17









Peyman mohseni kiasariPeyman mohseni kiasari

14911




14911








  • 1




    $begingroup$
    I actually computed the pdf of $X^2$ for a general random variable here: math.stackexchange.com/a/3043502/90543
    $endgroup$
    – jgon
    Dec 23 '18 at 17:21










  • $begingroup$
    @jgon thank you. it was hard for me to understand your answer because I'm very new to it, but finally, I get it. so I was right, it is not that simple that in the basic tutorials they just integral $int_{- infty}^infty x^2 p(x) d_x $ to find the Expected. nice answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 17:36














  • 1




    $begingroup$
    I actually computed the pdf of $X^2$ for a general random variable here: math.stackexchange.com/a/3043502/90543
    $endgroup$
    – jgon
    Dec 23 '18 at 17:21










  • $begingroup$
    @jgon thank you. it was hard for me to understand your answer because I'm very new to it, but finally, I get it. so I was right, it is not that simple that in the basic tutorials they just integral $int_{- infty}^infty x^2 p(x) d_x $ to find the Expected. nice answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 17:36








1




1




$begingroup$
I actually computed the pdf of $X^2$ for a general random variable here: math.stackexchange.com/a/3043502/90543
$endgroup$
– jgon
Dec 23 '18 at 17:21




$begingroup$
I actually computed the pdf of $X^2$ for a general random variable here: math.stackexchange.com/a/3043502/90543
$endgroup$
– jgon
Dec 23 '18 at 17:21












$begingroup$
@jgon thank you. it was hard for me to understand your answer because I'm very new to it, but finally, I get it. so I was right, it is not that simple that in the basic tutorials they just integral $int_{- infty}^infty x^2 p(x) d_x $ to find the Expected. nice answer.
$endgroup$
– Peyman mohseni kiasari
Dec 23 '18 at 17:36




$begingroup$
@jgon thank you. it was hard for me to understand your answer because I'm very new to it, but finally, I get it. so I was right, it is not that simple that in the basic tutorials they just integral $int_{- infty}^infty x^2 p(x) d_x $ to find the Expected. nice answer.
$endgroup$
– Peyman mohseni kiasari
Dec 23 '18 at 17:36










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