#math - Tue 20 Feb 2007 between 22:12 and 22:32

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JIMJONESBALLINanubiss, use brackets for open intervals.
(5, +infty)
anubisssorry
k
me22"anubiss> but if the domain is ok on the denominator, it wil be ok on the numerator for sure..." <-- not necessarily. Sqrt[x]/(|x|+1) the denominator is "good" everywhere, but the numerator isn't.
so the domain is [0,inf) despite the denominator being defined for all |R
anubissk
is it possible to calculate the derivative of an absolute function ^
?
me22not at the "corner"
anubisscomplicate stuff
me22you just do the 2 parts separately
anubissthen id write +-
me22d|x|/dx = { 1 for x >0, -1 for x <0 }
anubissis the use of the conjugate is ok?
me22?
anubisssay i want to calculate a limit
lim x->1 (sqrt(x) - 1 ) / (x-1)
i would do
ihopeMy simple set theory has one axiom.
anubisslim x->1 (sqrt(x) - 1 ) / (x-1) * (sqrt(x) +1) / (sqrt(x) +1)
ihopeComprehension: given a predicate on sets, there is a set containing exactly those sets matching the predicate iff the predicate doesn't match as many sets as p(x) = T does.
Of course, you might want to add more axioms to it, like one guaranteeing the existance of sets.
This one axiom doesn't guarantee any.
__mikemdoes anyone know why applying the rische integration algorythm on tan x doesn't give ln(sec x)
Kasadkad__mikem: What does it give?
__mikemln(some long expression that definitely does NOT equal sec x)
KasadkadYou sure it doesn't?
ihope% Integrate[Tan[x]]
mbotihope:
Integrate::argmu: Integrate called with 1 argument; 2 or more arguments are expected.
Integrate[Tan[x]]
ihopeWell, that sure didn't give Log[Sec[x]] :-P
diseaseris there an easy algebraic rule for factoring something like: x^4 - 1 ?
me22ihope : you forgot the ,x
__mikemlog(sin(2*x)^2+cos(2*x)^2+2*cos(2*x)+1)/2 this is what maxima got
me22diseaser : difference of squares
ihopeMy guess is this Rische integration algorithm isn't plain old integral.
me22anubiss : that's not a conjugate.
diseaserme22: cool thanks

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