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    Divergence operator in cylindrical & sherical

    look for some proof for the formula of the divergence operator in cylindrical & spherical coordinate is there any on the net ? TNX ! the formula here: http://hyperphysics.phy-astr.gsu.edu/hbase/diverg.html
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    Negative volume ?

    negative volume ??? attached herewith pdf file with the problem and my solution .
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    Need help volume calculation .

    ok.. thank you very much i am appreciate your help. by the way my picture is V for the uvz axis and not xyz .
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    Need help volume calculation .

    cotan(t) = cos(t)/sit(t) the limits of integration on u & v simply received from the projection of the region bounded by V on the UV plane -> you can see it circle with radius R=1 . the limits of integration on z: you can see in sketch : 0<=z<=U+V (of course just for u & v that in...
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    Need help volume calculation .

    attached herewith : the problem with my attempt to solve it .
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    The generalization of Newton's 2nd Law to apply to variable mass systems

    F = dp/dt = d(mv)/dt = m(dv/dt) + v(dm/dt) = a + v(dm/dt) i dont understand why d(mv)/dt = m(dv/dt) + v(dm/dt) can somone help ? TNX !:smile:
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    Limit problem calculate

    need to calculate lim X->infinity of x*[1/x] , while [] represent floor function . TNX.
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    Volume problem

    hello ! need to find the volume of V: { x^2+y^2=z , x^4+y^4=1 } i dont know how to set up the triple integral caue i didnt find any way to understand the surface projection on the xy plane . I would appreciate any help ....
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    Problem with integrating factor

    what next ? TNX !
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    Calculate the limit of the series

    hello Dick ! first of all tnx. i cant use l'Hopital's theorem cause n =1,2,3..... so F(n) not differentiable .
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    Calculate the limit of the series

    need to calculate the limit of the series (cos(a/n))^(n^3) n goes to infinity and a=!0 i try that : e^L L= the limit of (n^3)*ln(cos(a/n)) what now ??? TNX !
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    Sum of 1/ln(n)^(ln(n)) from n=3 to infinity?

    nope , you are magician , how u did it ? TNX !
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    Sum of 1/ln(n)^(ln(n)) from n=3 to infinity?

    Sum of 1/ln(n)^(ln(n)) from n=3 to infinity? Does the sum of 1/ln(n)^(ln(n)) from n=3 to infinity converge or diverge? TNX ...............
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    Differential equation

    it`s o k . TNX
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    Differential equation

    can u write cant understand . TNX .
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    Differential equation

    Homework Statement y`=(xy-y^2)/x^2 The Attempt at a Solution y` = y/x -(y/x)^2 {y/x=z , y=zx , y`=z+xz`} -z^2=x*dz/dx -z^2dx = xdz what`s next ? TNX . :smile:
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    Bounded function prove

    hello HallsofIvy ! , " I assume you mean prove that f is bounded in [a, infinity)." that is right , i dont understand why did u choose epsilon=1 is it necessary ? TNX!!
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    Bounded function prove

    need to prove that f(x) bounded if f(x) continuous in [a,+infinite] and if theres a limit while x goes to +infinite. I would really appreciate any kind of help !
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    Unite series convergence

    thres two series An and Bn , Bn unite with An from some index. need to prove that limAn_k = limBn_m Bn_m and An_m are sub series . TNX !!!
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    Cauchys criterion

    give me a reason y i cant pick p=1 and bout the Sn Sn= sum of the series from a1 to an .
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    Cauchy Criterion for Series limit

    so..... is it right ?
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    Cauchys criterion

    ?????????????????????????? ????????????????????? ??????? ??? ?
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    Cauchy Criterion for Series limit

    need to prove theres limit by cauchy criterion http://mathworld.wolfram.com/CauchyCriterion.html the sequence: {X_n}=(10/1)(11/3).....(n+9/2n-1) my try : is that right ? http://img155.imageshack.us/my.php?image=22221wl0.jpg
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    Cauchys criterion

    need to prove theres limit by cauchy criterion http://mathworld.wolfram.com/CauchyCriterion.html the sequence: {X_n}=(10/1)(11/3).....(n+9/2n-1) my try : is that right ? http://img155.imageshack.us/my.php?image=22221wl0.jpg
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    How to calculate the limits ?

    n!/n^n 2^n/n! n!/2^n 1/n + [1 + (-1)^n] / [2^(1/n)]
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    How to calculate the limits ?

    how to calculate the limits ? appreciate any kind of help ...
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    Neeed help in prove

    Analysis, for x and y that x<y
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