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Analysis and Calculus

From basic sequences, series and calculus, to measure theory, complex analysis and more advanced topics.

  1. Started by triclino,

    Given that: [math] f: [0,\infty)\rightarrow R[/math],such that [math]f(x)=\sqrt{x+1}[/math] prove that: [math] lim_{x\to 0}\sqrt{x+1} = 1[/math] using the ε-δ definition

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  2. Started by Martin,

    I guess everybody should know how to calculate the falling time at approximately uniform acceleration. Here's a problem. Say Milky masses a trillion (10^12) solar and there is nothing else around and you release a brick at a distance of 3 million lightyears. How long does it take to fall 0.5 million light years? It's elementary. Type this into google: sqrt(9 million (light year)^3/(G*mass of sun)) I've canceled 10^12 in the numerator and in the denominator. Otherwise it is just (approx.) uniform acceleration GM/r^2 and distance fallen = (1/2)a t^2. the point is that google calculator is a remarkable tool because it handles all the units for you. It kn…

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  3. Started by triclino,

    Suppose that ; 1)[math] f: R\rightarrow R^2[/math] such that : [math]f(x) =(2x+1,x^2)[/math] 2)The Euclidian norm of a vector [math] v=(u_{1}, u_{2})[/math] is defined as : [math] ||v||_{Eu} =\sqrt{ u_{1}^2 +u_{2}^2}[/math] 3) The maxnorm of a vector [math] v=(u_{1},u_{2})[/math] is defined as : [math] ||v||_{max} = max( |u_{1}|,|u_{2}|)[/math] Where [math] u_{1},u_{2}[/math] belong to the real Nos R Then prove : [math] \lim_{x\to 0} f(x) = (1,0)[/math] ,with respect to both norms

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  4. Started by triclino,

    prove that the sequence ln n diverges to infinity

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  5. Started by triclino,

    Prove that the the sequence [math] n^2[/math] diverges to infinity

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  6. Started by triclino,

    prove using the ε-definition,that : ln n is not a Cauchy sequence

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  7. Started by tsunamiBTP,

    I have attached a pdf of output from MAPLE attempting to evaluate an integral of an exponential function containing a complex irrational trig function as the exponent. MAPLE could not evaluate it when integrating with respect to the hangle phi. I then transformed the integral via varible substitutions to hopefully get it in a form that might be executable, but no luck there either. Any suggestions? This integral is a portion of a solution of a radiation wave emanating in the vicinity of source that is configured as a disc. integral output.pdf

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  8. Started by psychlone,

    Hi to all, I was wondering if any of the scienceforum.net sub forums have any URL addresses written specifically to access RSS Feeds? psychlone.

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  9. Started by triclino,

    Suppose that the sequence [math] S_{n}[/math] diverges to [math]+\infty[/math]. Now if [math]S_{n}[/math] does not diverge to [math]+\infty[/math] , does that imply that [math]S_{n}[/math] goes to a limit s

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  10. Started by inkliing,

    Hi. In 3 dimensional Euclidean space with the usual metric, d=[(delta x)^2+(delta y)^2+(delta z)^2]^1/2, I'm trying to figure out the average distance between nearest neighbors in a randomly distributed sample of particles. My best initial guess for the average distance from any given particle to its nearest neighbor is d_nearest neighbor_mean=(volume/n)^1/3 where n particles are randomly distributed in a 3 dimensional volume. The question originated when I wondered what was the average distance between stars in the solar neighborhood. atlasoftheuniverse.com gives 35 stars (including the Sun) within 12.5 light-years, and the above formula yields 6.16 ly as the avg di…

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  11. Started by triclino,

    I presented a professor with the following proof: Prove that the empty set is closed. Proof : By definition : [math]\emptyset[/math] is closed <=> cl[math]\emptyset\subseteq\emptyset[/math] <=> ([math]x\in[/math] cl [math]\emptyset[/math]=>[math]x\in\emptyset[/math]) cl [math]\emptyset[/math] is the closure of the empty set,and B(x,r) is a ball of radius r round x But ,by definition again [math]x\in[/math]cl [math]\emptyset[/math] <=> for all r>0 ,B(x,r)[math]\cap\emptyset\neq\emptyset[/math]....................................................................1 But , B(x,r)[math]\cap\emptyset =\emptyset[/math] => (…

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  12. Started by triclino,

    is the empty set bounded from above? has it got a supremum (l.u.b)? Whether it has or not how can we prove that??

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  13. Started by Tracker,

    Why is [math] \lim_{t\to0} \frac{\sin(t) }{t} = 1 [/math]

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  14. Started by alejandrito20,

    Hello. In maple: the signum function is signum(x)=x/|x| the derivate is d/dx {signum(x)}=signum(1,x) what is: signum(1,1,0) signum(1,x,0) signum(0,x,0) ????

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  15. Started by alejandrito20,

    For my thesis I need to solve many differential equations non linear, second order by using maple.... For example figure adjoint using dsolve command, the solutions are very extensives and very bad. there is a suggest for to solve the differential equations by using maple? there is some methods in maple to find the aproximate solution? thanks

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  16. Started by alejandrito20,

    any suggestions to solve the follows differential equations by using maple??? see adjoint figure

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  17. Started by Cyanide,

    Note: This isn't graded work, it's the basics.. Use the Chain Rule to get dw/dt when, w = cos(x-y) x = t^2 y = sin t I know dw/dt = (dw/dx)(dx/dt)+(dw/dy)(dy/dt) Thus far I have, dw/dt = (-sin(x)-cos(y))(2t)+(cos(x)+sin(y))(cos(t)) Substituting in x and y.. dw/dt = (-sin(t^2)-cos(sint)(2t))+(cos(t^2)+sin(sint)(cost)) I feel like I have done something wrong (I don't have the solution to this problem)..but I know it doesn't look correct. I'm thinking that perhaps I made a mistake with the derivatives and it should be something closer to.. dw/dt = ((cos(x))(2t))+((sin(y)(cost)) dw/dt = ((cos(t^2))(2t))+((sin(sint))(cost)) But again, I'm cluel…

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  18. Started by ChemSiddiqui,

    Hi everyone, I have been trying to practice calculus for the benfit of my quantum mechanics studies and I am stuck with a problem so thought you people might have some advice to give.Here goes; [math] \frac{d sin\theta}{d(\theta)cos(\theta)} sin(\theta)sin(\phi)[/math] Now we have to operate the [math] \frac{d sin(\theta)}{d(\theta)cos(\theta)} [/math] onto function [math] sin(\theta)sin(\phi)[/math]. The operator can expressed into [math] cos^2(\theta)-sin^2(\theta) [/math] after diffentiation. Now my question is that can I simply multiply this by [math] sin(\theta)sin(\phi)[/math] or will this be wrong? It would have been much easier if the expres…

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  19. The definition of the partial derivative of [math]f[/math] with respect to [math]x[/math] is [math]\frac{\partial f}{\partial x} = \frac{f(x+\mathrm{d}x,y,z)-f(x,y,z)}{\mathrm{d}x}[/math] right? While [math]\mathrm{d}x[/math] has a meaning, an infinitesimal change in [math]x[/math], what does [math]\partial x[/math] mean?

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  20. Started by Garrettguy457,

    Simple question. Is rolling a six-sided dice that has 5 sides with a 1 and 1 side with a 6 random? Not a 1-6 dice. Or is rolling two dice random?

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  21. Started by hobz,

    I am currently reading about the divergence and I am curious what is gained by reformulating stuff like Gauss law from integral form into differential form? The expressions become shorter and nicer, but surely there must be another reason?

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  22. What is the value of x for these equations? a. Find all solutions for this equation: (e^2x)-(6e^x)+32/4=0 b.(e^x)-24e^(-x)=-2 Use common logs to solve for x in terms of y for the following: c.y=10^x+10^(-x) ----------------- 18 I don't know even where to start. . . I'd apprecite all the help possible.

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  23. Started by kleinwolf,

    Is it possible to express [math]\sin(4x)[/math] in terms of [math]\sin(x),\sin(2x),\sin(3x)[/math] only ??

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  24. Started by triclino,

    CAN somebody,please write the definition for the linear independence of the following functions?? [math] e^x,e^{2x}[/math]

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  25. Started by Cap'n Refsmmat,

    Today's calculus warmup question has stumped everyone in the class, including our teacher. Here's the question: [math]\lim_{x\to 0} x^{\sin x}[/math] We can't think of any safe way to evaluate the limit. We tried rewriting the problem to this: [math]y = \lim_{x\to 0} x^{\sin x}[/math] and then changing to this: [math]\ln y = \lim_{x\to 0}\sin x \ln x[/math] but in the end it didn't help. Any ideas? [hide]The answer turns out to be 1, but we have no idea to get it.[/hide]

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