Recent content by adoado

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    Potassium Nitrate Products

    The combination of potassium nitrate and sorbitol and commonly used by hobbyists as a propellant for rocket motors. The combustion equation is given below: I have a few very simple questions based on the chemistry of such a reaction. Firstly, many people do not use stoichiometric...
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    DC vs AC Safety: What You Need to Know

    Awesome, thanks a lot for the replies! Using your myspeedybob as a guide, I found this: http://www.tpub.com/content/et/14086/css/14086_34.htm It explains pretty much exactly what you said. So I guess as a general rule, assume the resistance of the body is R = 1500 Ω. Then, find the current...
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    DC vs AC Safety: What You Need to Know

    Hey guys, My understanding of circuit analysis and the like is very minimal, and I have had a certain lack of understanding about something for a long time, and I feel I need to get a solid answer. I understand the fundamental difference between a voltage or potential difference and a...
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    Integer solution to exponential diophantine equation

    Hey everyone! I was recently scribbling on paper, and after a series of ideas, I got stuck with a problem. That is, can I find out if there exists some integers A and B such that C=2^{A}3^{B} For some integer C? For an arbitrary C, how do I know whether some A, B \in \textbf{Z}...
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    Finding Bestfit Distribution [image]

    I use CurveExpert to find best fit models; give that a try. Then simply evaluate a few points from the model and plot them as separate data.
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    Permutation and total values

    Hey all, I recently encountered a problem that I cannot seem to solve... Let's say I have the following coins A, B, C, D and E, each one with an associated integer value such that: A = 1 B = 2 C = 3 D = 4 E = 5 Let's say I can pick N of them, and order does matter (so ABC is not...
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    How do I find the intersection of 4D lines?

    Hello all, Given two 3D lines described by the general equation \vec{L(t)}=\vec{p}+\vec{d}t I found a way to find their intersection point, but it uses the cross product in the derivation. I am assuming a 4D line is a valid thing? And can be described the same way? (except with 4 element...
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    Calculators Is my TI-89 calculator correctly expanding partial fractions?

    Clear the variables; if you have stored x as a constant (given it a value) then you will get a numerical result.
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    Minimizing Sum of Absolute Values

    Awesome, thanks a lot Redbelly! Really appreciate that! :)
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    Minimizing Sum of Absolute Values

    I am not sure the reasoning to it, or exactly what you mean :tongue2: Able to elaborate on the reasoning of this? Cheers! Adrian
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    Minimizing Sum of Absolute Values

    I recently encountered another problem, but it extends this topic. Instead of opening a new thread I guess this place is as good as any.. If one defines the function E=|1-x-y| + |4-2x-y| ... how can I find it's minimum now (x and y coordinates)? Can this be extended to N variables inside each...
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    Sums of Integer Powers - C(s) Convergence

    Hello all, Is there a closed form expression for the convergence of C(s) = \sum_{n=1}^{N} n^{s} Cheers, Adrian
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    Find general solution, 1st order ODE

    Isn't that separable? Split up the differentials?
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    Solving Strange Derivative: Find (df/dt)(0)

    Hmm... you can still get x'(t) and y'(t) by differentiating implicitly t(x) and t(y), but you will be left with derivatives still partially in terms of x and y... Edit: I am not sure if this is valid, but as you are evaluating the final derivative at t=0, why not do it to all the partial...
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    Solving Strange Derivative: Find (df/dt)(0)

    If you have done this, then try the chain rule (http://en.wikipedia.org/wiki/Chain_rule) but use partial derivatives. if you have x(t) and y(t) then \frac{df}{dt} can be found by \frac{df}{dt}=\frac{\partial f}{\partial x}\frac{\partial x}{\partial t} + \frac{\partial f}{\partial...
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