What is Series: Definition and 998 Discussions

In mathematics, the Taylor series of a function is an infinite sum of terms that are expressed in terms of the function's derivatives at a single point. For most common functions, the function and the sum of its Taylor series are equal near this point. Taylor's series are named after Brook Taylor, who introduced them in 1715.
If zero is the point where the derivatives are considered, a Taylor series is also called a Maclaurin series, after Colin Maclaurin, who made extensive use of this special case of Taylor series in the 18th century.
The partial sum formed by the first n + 1 terms of a Taylor series is a polynomial of degree n that is called the nth Taylor polynomial of the function. Taylor polynomials are approximations of a function, which become generally better as n increases. Taylor's theorem gives quantitative estimates on the error introduced by the use of such approximations. If the Taylor series of a function is convergent, its sum is the limit of the infinite sequence of the Taylor polynomials. A function may differ from the sum of its Taylor series, even if its Taylor series is convergent. A function is analytic at a point x if it is equal to the sum of its Taylor series in some open interval (or open disk in the complex plane) containing x. This implies that the function is analytic at every point of the interval (or disk).

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  1. LCSphysicist

    Why do we need to equate the rate of energy of the second plate to zero?

    First i computed the rate of energy wrt time of the second plate: $$dq_{2}/dt = A \sigma ((373)^4/2 + (273)^4/2 - T_{2}^4)$$ Equaliting it to zero we get the answer. But i am not sure why do we need to equality it to zero. The q arrow on the figure suggest me that it is conservation of energy...
  2. H

    Explanation of the spectrochemical series of transition metal ions

    The spectrochemical series of metals, under the circumstances that same ligands are used and that it is in an octahedral coordination, is given by: Mn2+ < Ni2+ < Co2+ < Fe2+ < V2+ < Fe3+ < V3+ < Co3+ < Mn4+ < Mo3+ < Rh3+ < Ru3+ < Pd4+ < Ir3+ < Pt4+ When I was skimming through a textbook to...
  3. R

    I LRC Series Circuit with an AC Source

    Attached is the section from the book. I am doing section 31.3 We know that an AC source gives a sinusoidal varying current, and as far as I know its always given by ##i(t) = Icos(wt)##. Its like we take the current to be the base of all other quantities, so we use it to derive everything else...
  4. F

    Lower Central Series - Understanding the Induction Process

    My attempt: If ##i = 1##, then ##\gamma_1 = G \rhd G' = \gamma_2##. We proceed by induction on ##i##. Consider an element ##xyx^{-1}y^{-1}## where ##x \in \gamma_i## and ##y \in G##. Since ##\gamma_i \rhd G##, we have ##yx^{-1}y^{-1} = x_0 \in \gamma_i##. So, ##xyx^{-1}y^{-1} = xx_0 \in \gamma_i...
  5. Purpleshinyrock

    B Can You Solve This Exercise on Arithmetic-Geometric Series?

    Hello, I am currently self studying sequence and series and I got to a topic called arithmetic-geometric sequence, and after the theory It gives this exercise: 1) Find the sum: S=1+11+111+1111+...+111...111, if the last (number) is a digit of n. I was given a tip That says that 1 = (10 - 1)/9...
  6. Ntip

    Designing Balancing Resistors for Series Capacitors: Factors Affecting IR

    I am lookin designing balancing resistors for series capacitors and understand that I need to consider the leakage current from the capacitors. I am trying to determine factors that would case the insulation resistance to decrease over time so I can design around that.
  7. greg_rack

    Charges of capacitors in series and in parallel

    Very simply, I can't understand why the charges of capacitors placed in series are all the same, and why even the total one(of the circuit) is equal to those. How is it possible that the total charge is the same as the individual ones? There must be some concept/property about capacitors which...
  8. S

    I Divergent series sum, versus integral from -1 to 0

    Some popular math videos point out that, for example, the value of -1/12 for the divergent sum 1 + 2 + 3 + 4 ... can be found by integrating n/2(n+1) from -1 to 0. We can easily verify a similar result for the sum of k^2, k^3 and so on. Is there an elementary way to connect this with the more...
  9. no_drama_llama_77

    I Fourier Series and Cepheid Variables

    If given a set of data points for the magnitude of a cepheid variable at a certain time (JD), how can we use Fourier series to find the period of the cepheid variable? I'm trying to do a math investigation (IB math investigation) on finding the period of the cepheid variable M31_V1 from data...
  10. P

    Coulomb's Law and Conditional Convergent Alternating Harmonic Series

    Mary Boas attempts to explain this by pointing out that the situation cannot arise because charges will have to be placed individually, and in an order, and that order would represent the order we sum in. That at any point the unplaced infinite charges would form an infinite divergent series...
  11. F

    Refining a normal series into a composition series

    Attempt: Consider an arbitrary normal series ##G = G_0 \ge G_1 \ge G_2 \ge \dots \ge G_n = 1##. We will refine this series into a composition series. We start by adding maximal normal subgroups in between ##G_0## and ##G_1##. If ##G_0/G_1## is simple, then we don't have to do anything. Choose...
  12. F

    Normal series and composition series

    Attempt so far: We're given that ##G## and ##H## have equivalent normal series $$G = G_0 \ge G_1 \ge \dots \ge G_n = 1$$ and $$H = H_0 \ge H_1 \ge \dots \ge H_n = 1$$ We can assume they have the same length because they are equivalent. I think from here I need to construct two composition...
  13. J

    Help with 2nd order Runge Kutta and series expansion

    So here's my homework question: This is the reference formula along with the Rung-Kutta form with the variables mentioned in the question Here is my attempt so far: Problem is that i am unsure how to expand this to even get going. I tried referencing my text Math Methods by Boas which has...
  14. fresh_42

    Changing the Statement Proving $\zeta(2)=\frac{\pi^2}{6}$ via Geometric Series & Substitutions

    Prove $$ \zeta(2) = \sum_{n\in \mathbb{N}}\dfrac{1}{n^2} = \dfrac{\pi^2}{6} $$ by evaluating $$ \int_0^1\int_0^1\dfrac{1}{1-xy}\,dx\,dy $$ twice: via the geometric series and via the substitutions ##u=\dfrac{y+x}{2}\, , \,v=\dfrac{y-x}{2}##.
  15. V

    I Infinite series calculation of a potential

    I'm trying to get from the formula in the top to the formula in the bottom (See image: Series). My approach was to complexify the sine term and then use the fact that (see image: Series 1) for the infinite sum of 1/ne^-n. Then use the identity (see image: Series 2). Any other ideas?
  16. E

    How to calculate the resistance of a series circuit?

    Why we say that the resistance of the series curcuit is equal to the sum of the resistances of the resistors?
  17. penroseandpaper

    Converging and diverging Series

    Would somebody be kind enough to check whether I've picked the right convergence tests for each of these and reached the right answers? There are no solutions in the book. Also, is there a method I can use to determine if I'm right - does calculating the first n terms help? Thank you Edit...
  18. E

    Why is the current the same in series circuits?

    If the current goes through the first end of the resistor will it be less than on the other end of resistor?
  19. anemone

    MHB Proving Series Inequality: $\sqrt[3]{\frac{2}{1}}$ to $\frac{1}{8961}$

    Prove that $\sqrt[3]{\dfrac{2}{1}}+\sqrt[3]{\dfrac{3}{2}}+\cdots+\sqrt[3]{\dfrac{996}{995}}-\dfrac{1989}{2}<\dfrac{1}{3}+\dfrac{1}{6}+\cdots+\dfrac{1}{8961}$.
  20. patric44

    Solving a Gaussian integral using a power series?

    hi guys i am trying to solve the Gaussian integral using the power series , and i am suck at some point : the idea was to use the following series : $$\lim_{x→∞}\sum_{n=0}^∞ \frac{(-1)^{n}}{2n+1}\;x^{2n+1} = \frac{\pi}{2}$$ to evaluate the Gaussian integral as its series some how slimier ...
  21. Hiero

    I Looking for references on this form of a Taylor series

    I was trying to find this form of the Taylor series online: $$\vec f(\vec x+\vec a) = \sum_{n=0}^{\infty}\frac{1}{n!}(\vec a \cdot \nabla)^n\vec f(\vec x)$$ But I can’t find it anywhere. Can someone confirm it’s validity and/or provide any links which mention it? It seems quite powerful to be...
  22. T

    Evaluate the Taylor series and find the error at a given point

    I have the following function $$f^{(0)}\left(x\right)=f\left(x\right)=e^{x}$$ And want to approximate it using Taylor at the point ##\frac{1}{\sqrt e} ## I also want to decide (without calculator)whether the error in the approximation is smaller than ##\frac{1}{25} ## The Taylor polynomial is...
  23. J

    A How Do You Solve This Alternating Series Involving Logarithms?

    Hi! Some time ago I came across a series and never solved it, I tried to give a new go because I was genuinely curious how to tackle it, which I thought would work, because it looks innocent, but there is something about the beast making it hard to approach for me. So need some help! Maybe this...
  24. J

    Engineering Simplifying a series / parallel circuit and calculating unknown values

    Given the circuit above, I have to solve for the labelled currents, find V total and R total accordingly. 1A is flowing through the 5Ω resistor as shown. Assuming electron flow (negative terminal to positive) for circuit. The connector in the middle was somewhat confusing. Without it, this...
  25. U

    I Conditional distribution of geometric series

    Can someone help me on this question? I'm finding a very strange probability distribution. Question: Suppose that x_1 and x_2 are independent with x_1 ~ geometric(p) and x_2 ~ geometric (1-p). That's x_1 has geometric distribution with parameter p and x_2 has geometric distribution with...
  26. HansBu

    Laurent Series (Complex Analysis)

    My homework is on mathematical physics and I want to know the concept behind Laurent series. I want to know clearly know the process behind attaining the series representation for the expansion in sigma notation using the formula that can be found on the attached files. There are three questions...
  27. AN630078

    Finding a and d from the Sum of an Arithmetic Series

    Question 1; Method 1 If the sum of the first four terms is 139 then S4=139 139=1/2(4)(2a+(4-1)d) 139=2(2a+3d) 139=4a+6d----- [1] The part of this question that is confusing is the "the sum of the next four terms is 115". Would this mean that S8=S4+115=139+115=254? In which case...
  28. rannasquaer

    MHB Dirac Delta and Fourier Series

    A beam of length L with fixed ends, has a concentrated force P applied in the center exactly in L / 2. In the differential equation: \[ \frac{d^4y(x)}{dx^4}=\frac{1}{\text{EI}}q(x) \] In which \[ q(x)= P \delta(x-\frac{L}{2}) \] P represents an infinitely concentrated charge distribution...
  29. C

    Job Skills APS: Success in Industry Careers Webinar Series

    The American Physical Society (APS) has just launched a webinar series addressing careers for physicists in industry (broadly includes national labs). [ETA: Correction: National labs are covered under a separate series also listed on the following link.] Details of the series can be found...
  30. jisbon

    Proving the Geometric Series with Variable Coefficients: A Scientific Approach

    So this seems to be a geometric Series, but with the coefficients in front, how do I exactly go about proving this? Thanks
  31. fresh_42

    Indirect Proof (open) Divergent series of inverse primes

    Show by contradiction that $$ \sum_{p\in \mathbb{P}}\dfrac{1}{p} =\sum_{p\;\text{prime}}\dfrac{1}{p} $$ diverges. Which famous result is an immediate corollary?
  32. T

    I A harmonic series without the nines

    The sum of the harmonic series(1/1+1/2+1/3...) is infinite. However, if you exclude all the terms that contain the number nine, the sum is just under 23. From 1 to 100 19% of the terms are excluded From 1 to 1000 27.1% of the terms are excluded Is there a formula for a N digit number what the...
  33. M

    How to 'shift' Fourier series to match the initial condition of this PDE?

    Hi, Question: If we have an initial condition, valid for -L \leq x \leq L : f(x) = \frac{40x}{L} how can I utilise a know Fourier series to get to the solution without doing the integration (I know the integral isn't tricky, but still this method might help out in other situations)? We are...
  34. M

    MHB Checking Convergence of Series: Inequalities & Tests

    Hey! 😊 I want to check the convergence for the below series. - $\displaystyle{\sum_{n=1}^{+\infty}\frac{\left (n!\right )^2}{\left (2n+1\right )!}4^n}$ Let $\displaystyle{a_n=\frac{\left (n!\right )^2}{\left (2n+1\right )!}\cdot 4^n}$. Then we have that \begin{align*}a_{n+1}&=\frac{\left...
  35. Imaxx

    B How to prove this infinite series?

    While transforming the equation of the Basel problem, the following infinite series was obtained. $$\sum_{n=1}^{\infty} \frac{n^2+3n+1}{n^4+2n^3+n^2}=2$$ However I couldn't think of a simple way to prove that. Can anyone prove that this equation holds true?
  36. Imaxx

    Is This Infinite Series Convergent?

    ∞ ∑ (n∧2+3n+1) / (n∧4+2n∧3+n∧2) =? n=1 I attempted to find the general sum of this 'expression'?? But no luck. How can I solve this?
  37. T

    MHB How to estimate simplex gradient using Taylor series?

    I read Iterative methods for optimization by C. Kelley (PDF) and I'm struggling to understand proof of Notes on notation: S is a simplex with vertices x_1 to x_{N+1} (order matters), some edges v_j = x_j - x_1 that make matrix V = (v_1, \dots, v_n) and \sigma_+(S) = \max_j \lVert...
  38. FourEyedRaven

    Netflix series DARK - Taking Sci-Fi Writing to a New Level

    Hi. Any fans of DARK here? This show was mind blowing. The feel of the show may be to heavy for some, especially in the beginning. So it may not be your style. But if you like that atmosphere, the series is truly amazing. The writing is on a whole new level. If you haven't watched it, I...
  39. C

    MHB Using Cauchy Integral Formula for Laurent Series Coefficients

    Dear Everyone, I am wondering how to use the integral formula for a holomorphic function at all points except a point that does not exist in function's analyticity. For instance, Let $f$ be defined as $$f(z)=\frac{z}{e^z-i}$$. $f$ is holomorphic everywhere except for $z_n=i\pi/2+2ni\pi$ for...
  40. jedishrfu

    Awesome Sci Fi Series that’s hard to explain

    I just watched season one of Tales from the Loop. It has the mood of Interstellar on the Earth where people live quiet lives of desperation. There’s an underground physics lab nicknamed the Loop where the impossible becomes possible. There’s the people whose lives are affected in strange ways...
  41. M

    I What is the Function for the Value of a Convergent Series Sum?

    ##\sum_n \frac{1}{n^c}## converges for ##c\gt 1##. Is there an expression for the value of the sum as a function of ##c##?
  42. agnimusayoti

    Fourier series for trigonometric absolute value function

    First, I try to define the function in the figure above: ##V(t)=100\left[sin(120\{pi}\right]##. Then, I use the fact that absolute value function is an even function, so only Fourier series only contain cosine terms. In other words, ##b_n = 0## Next, I want to determine Fourier coefficient...
  43. Adesh

    Analysis Books for learning Fourier series expansion

    Hello Everyone! I want to learn about Fourier series (not Fourier transform), that is approximating a continuous periodic function with something like this ##a_0 \sum_{n=1}^{\infty} (a_n \cos nt + b_n \sin nt)##. I tried some videos and lecture notes that I could find with a google search but...
  44. Leo Liu

    I A Sequence in a Power Series

    I tried to use the ratio test, but I am stuck on finding the range of the limit. $$\because \left|x-1\right|<1.5=Radius$$ $$\therefore -0.5<x<2.5$$ $$\lim _{n \to \infty} \left| \frac{A_{n+1}(x-1)^{n+1}}{A_n(x-1)^n} \right|$$ $$\lim_{n \to \infty} \frac{A_{n+1} \left|x-1\right|}{A_n} <1$$...
  45. PainterGuy

    I Questions about this video on Taylor series

    Hi, I was watching a video on the origin of Taylor Series shown at the bottom. Question 1: The following screenshot was taken at 2:06. The following is said between 01:56 - 02:05: Halley gives these two sets of equations for finding nth roots which we can generalize coming up with one...
  46. WMDhamnekar

    MHB Solve Math Problem: Mixing Milk & Water to Get 50% Milk

    Hi, A person has 40 litres of milk. As soon as he sells half a litre, he mixes the remainder with half a litre of water. How often can he repeat the process, before the amount of milk in the mixture is 50% of the whole? Detailed explanation is appreciated.:) Solution: I am working on...
  47. JD_PM

    Series expansion of the Lorentz Transformation

    a) I think I got this one (I have to thank samalkhaiat and PeroK for helping me with the training in LTs :) ) $$\eta_{\mu\nu}\Big(\delta^{\mu}_{\rho} + \epsilon^{\mu}_{ \ \ \rho} +\frac{1}{2!} \epsilon^{\mu}_{ \ \ \lambda}\epsilon^{\lambda}_{ \ \ \rho}+ \ ...\Big)\Big(\delta^{\nu}_{\sigma} +...
  48. Adesh

    Capacitors connected in series: Why is the voltage the same?

    Here is a circuit diagram: . We have three capacitors, with capacitances ##C_1##, ##C_2## and ##C_3##. Plates are labelled as ##A_1, A_2, A_3 ... A_6##. Point P is connected to the positive terminal of the battery and point N is connected to the negative terminal of the...
  49. rachelmaddiee

    Voltage drops in a series circuit

    Known: V source = 30.0 V , R1 = 15.0 W, R2 = 15.0 W, R3 = 15.0 W To determine the current, first find the equivalent resistance. I = Vsource/R and R = RA + RB = Vsource/RA + RB 30.0 V/15.0 W + 15.0 W + 15.0 W = 1.5 A This is as far as I could do the work for this question. I’m having trouble..
  50. N

    I A question about operator power series

    Hi All, I've been going through Shankar's 'Principles of Quantum Mechanics' and I don't quite understand the point the author is trying to make in this exercise. I get that this wavefunction is not a solution to the Schrodinger equation as it is not continuous at the boundaries and neither is...
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