Sequence and series Definition and 22 Threads

  1. K

    B Sequence formula needed - Keyword --> annuity

    Below is a screenshot of an insurance policy: I was told by the insurance company that the return becomes lower and lower with the age till death increasing. And this reduction in return is by an annuity ratio of 6%. I wanted to find out the formula so that I can understand the effect of...
  2. H

    Doubt regarding the series ##\sum [\sqrt{n+1} - \sqrt{n}\,]##

    We're given the series ##\sum_{n=1}^{\infty} [ \sqrt{n+1} - \sqrt{n} ]##. ##s_n = \sqrt{n+1} - 1## ##s_n## is, of course, an increasing sequence, and unbounded, given any ##M \gt 0##, we have ##N = M^2 +2M## such that ##n \gt N \implies s_n \gt M##. Thus, the series must be divergent. But...
  3. Vividly

    B Understanding about Sequences and Series

    Homework Statement:: Tell me if a sequence or series diverges or converges Relevant Equations:: Geometric series, Telescoping series, Sequences. If I have a sequence equation can I tell if it converges or diverges by taking its limit or plugging in numbers to see what it goes too? Also if I...
  4. Fochina

    Finding the convergence of a parametric series

    It is clear that the terms of the sequence tend to zero when n tends to infinity (for some α) but I cannot find a method that allows me to understand for which of them the sum converges. Neither the root criterion nor that of the relationship seem to work. I tried to replace ##\sqrt[n]{n}## with...
  5. C

    I ##(a_n) ## has +10,-10 as partial limits. Then 0 is also a partial limit

    Problem: If sequence ## (a_n) ## has ##10-10## as partial limits and in addition ##\forall n \in \mathbb{N}.|a_{n+1} − a_{n} |≤ \frac{1}{n} ##, then 0 is a partial limit of ## (a_n) ##. Proof : Suppose that ## 0 ## isn't a partial limit of ## (a_n) ##. Then there exists ## \epsilon_0 > 0 ## and...
  6. CoffeeNerd999

    I Do I need induction to prove that this sequence is monotonic?

    I think the initial assumptions would allow me to prove this without induction. Suppose ##(x_n)## is a real sequence that is bounded above. Define $$ y_n = \sup\{x_j | j \geq n\}.$$ Let ##n \in \mathbb{N}##. Then for all ##j \in \mathbb{N}## such that ##j \geq n + 1 > n## $$ x_{j} \leq y_n.$$...
  7. Physics lover

    Sum of a series that tends to infinity

    I tried by ##S=1+(1/1!)(1/4)+(1.3/2!)(1/4)^2+...## ##S/4=1/4+(1/1!)(1/4)^2+(1.3/2!)(1/4)^3..## And then subtracting the two equations but i arrived at nothing What shall i do further?
  8. D

    MHB Sum of pqth Term in Arithmetic Progression

    The pth term of an airthmetic progression is 1/q and qth term is 1/p. What is the sum of pqth term?
  9. Mr Davis 97

    Sequence and Series Terminology

    First, I would like to clear up notation and the definition for sequences. What exactly is a sequence? I read somewhere that it is defined as a function ##f: \mathbb{N} \to \mathbb{R}##. But if this is the case, why do we only define functions based on the range of the function, e.g., ##\left \{...
  10. D

    What is the sum of cubes in a series up to 'n' terms?

    Homework Statement find the sum of the series to 'n' terms (1^3 / 1 ) + (1^3 + 2^3 / 1+2 ) + (1^3 + 2^3 + 3^3 / 1+2+3 ) +... Homework Equations sigma n^2 = n(n+1)(2n+1) / 6 sigma n = n(n+1) / 2 The Attempt at a Solution numerator = 1^3 + 2^3 + ... n^3 denominator = 1+2+3+...n...
  11. N

    Sequence and series - Arithmetic mean question have been breaking my head

    Homework Statement Two consecutive numbers from 1,2,3...n are removed A.M of remaining numbers is 105/4. Find n and those numbers removed .Homework Equations Answer n = 50 those numbers are 7 and 8 The Attempt at a Solution I solved this question like a few weeks ago but now it escaped my...
  12. G

    Definition of sequence and series

    Hi! While studying sequence and series, I've gotten some misunderstandings in the definitions of sequence and series. What I know about the definitions of sequence and series is as follows below ; a sequence of field of real numbers is defined as a function mapping of the set of all positive...
  13. E

    Sequence and Series question (maybe)?

    Homework Statement Find all positive integers n such that both n + 2008 divides n^2 + 2008 and n + 2009 divides n^2 + 2009 Homework Equations - The Attempt at a Solution I have no idea where to start... I'm not even sure it's a sequence and series question. If it is then I have...
  14. L

    Sequence and Series Reconstruction

    After studying Generating Functions some, I wondered this question: 1). Take an arbitrary sequence of numbers for example: {p1,p2,p3,p4...pN} and get/find a Generating Function for that sequence. 2). Now 'remove' an arbitrary sequence members from the above set :{p1,p2,p3,p4...p100}...
  15. N

    Representing Sequence 1*3*5*7*9... with Factorials for Calculator Use

    is there a way to represent the sequence 1*3*5*7*9...(2n-1) for n>=1 with a factorial if not is thre a way to input that sequence ino a calculator with somthing
  16. X

    How Do You Solve Challenging Limits and Analyze Sequence Monotonicity?

    Got a couple questions please help! 1. lim n>inf (x^4)/(e^(-2x)) How do you do this one? i know you use L hospital rule but you can never get rid of the denominator. or is there a trick i am missing? 2. Determine whether the sequences are increasing, decreasing, or not monotonic...
  17. H

    Solving Sequence and Series Limits: xn = 1/ln(n+1)

    Homework Statement Let xn = 1/ln(n+1) for n in N. a) Use the definition of limit to show that lim(xn) = 0. b) Find a specific value of K(ε) as required in the definition of limit for each of i)ε=1/2, and ii)ε=1/10. The Attempt at a Solution a) If ε > 0 is given, 1/ln(n+1) < ε <=>...
  18. M

    Sequence and Series, finding relationship

    Homework Statement 0<y0<x0 x1=(x0+y0)/2 y1=\sqrt{x0y0} in general Xn+1=(xn+yn)/2 Yn+1=\sqrt{XnYn} Homework Equations none The Attempt at a Solution I have no idea I tried to solve for Xn and substituting that into another equation... however, I don't know how to simplify...
  19. N

    Expert Sequence and Series Assistance | Dave's Math Help

    There was this awesome help site for this topic. The name of it was something like "Dave's math help". I thought I saved the link but guess I didn't. Anyone know where I could possibly find this site or know of others?
  20. A

    Sequence and series word problem

    Tod injured his wrist while he was skateboarding. To relive the pain his doctor prescribed him some medication. He takes 500mg of medicine every 6h. Only 25 % of the medication remains in his body by the time he is ready to take another pill. Write and equation to model this. so 25% is...
  21. N

    Proving Cube Numbers Not in Sequence a_n=3n+2

    Right here is my sequence 2, 5, 8, 11, 14, ... I have been asked to prove that the cube of any number in the sequence is in the sequence. my answer: General term: a_n=3n+2 We need to cube a_n and see if it matches a number in the series i.e. (a_n)^3 = 3q+2 for some integer q...
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