Mathematics
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OpenStudy (anonymous):
what is the expected value of x^2 in mathematical form?
12 years ago
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OpenStudy (anonymous):
in a simplified form
12 years ago
OpenStudy (lgbasallote):
what do you mean?
12 years ago
Parth (parthkohli):
\(x \times x\) I think that's what you mean.
12 years ago
OpenStudy (anonymous):
yeah
12 years ago
OpenStudy (lgbasallote):
mathematical form?
12 years ago
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Parth (parthkohli):
Hmm. Similarly:
\( \color{Black}{\Rightarrow x^3 = x \times x\times x}\)
\( \color{Black}{\Rightarrow x^4 = x \times x \times x \times x}\)
12 years ago
Parth (parthkohli):
'Mathematical form' is still ambiguous.
12 years ago
OpenStudy (anonymous):
some stats people know may know
12 years ago
OpenStudy (unklerhaukus):
\[\langle x^2\rangle =\sum\limits_{j=0}^\infty x^2 P(j)\]
12 years ago
Parth (parthkohli):
lol
12 years ago
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OpenStudy (lgbasallote):
\[\int 2xdx\]
12 years ago
OpenStudy (anonymous):
this reminds me of a very fundamental/basic question in calculus..please see my next question..i'll post link..
12 years ago
OpenStudy (lgbasallote):
\[\frac{d}{dx} (\frac{x^3}{3})\]
12 years ago
OpenStudy (unklerhaukus):
what are you doing at @lgbasallote ,
12 years ago
OpenStudy (lgbasallote):
\[x^2 = r^2 - y^2\]
12 years ago
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OpenStudy (lgbasallote):
trying to get all that's x^2 and see if anythign suits him
12 years ago
OpenStudy (unklerhaukus):
im pretty sure i have provided the answer to the question
12 years ago
OpenStudy (lgbasallote):
we all think that...
12 years ago
OpenStudy (unklerhaukus):
,oh
12 years ago
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OpenStudy (anonymous):
i need E(x^2)=?
12 years ago
OpenStudy (unklerhaukus):
the expectiation value of \(x\) \[\langle x\rangle =E(x)\]
12 years ago
OpenStudy (anonymous):
@UnkleRhaukus yes but x^2
12 years ago
OpenStudy (lalaly):
\[Var(x)=E(x^2)-(E(x))^2\]
12 years ago
OpenStudy (anonymous):
i got the ans... thanks all
12 years ago
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OpenStudy (unklerhaukus):
\[\sigma_x=\langle x^2\rangle-\langle x\rangle ^2\]
12 years ago
OpenStudy (lalaly):
:D
12 years ago
OpenStudy (anonymous):
ya ur right
12 years ago
OpenStudy (unklerhaukus):
The expectation value , or expect value of a function
is \[\langle f(x)\rangle =\sum\limits_{x=0}^\infty f(x)P(x)\]
where \(P(x)\) is the probability of x
12 years ago
OpenStudy (anonymous):
yes for a discrete random variable
12 years ago
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OpenStudy (unklerhaukus):
im not sure why i put j instead of x,
12 years ago
OpenStudy (unklerhaukus):
oh, you want a continuous function?
12 years ago
OpenStudy (anonymous):
no i know
12 years ago
OpenStudy (anonymous):
thank you
12 years ago
OpenStudy (unklerhaukus):
\[\langle f(x)\rangle=\int\limits_{-\infty}^\infty f(x)\rho(x)\text dx\]
12 years ago
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OpenStudy (anonymous):
ya
12 years ago
OpenStudy (unklerhaukus):
where \(\rho(x)\) is the probability density
12 years ago
OpenStudy (unklerhaukus):
so
\[\langle x^2\rangle=\int\limits_{-\infty}^\infty x^2\rho(x)\text dx\]
12 years ago
OpenStudy (anonymous):
@UnkleRhaukus small question the E(constant) is a constant right
12 years ago
OpenStudy (unklerhaukus):
if the distribution of the variable \(x\) is constant , yes
12 years ago
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OpenStudy (anonymous):
thanks
12 years ago