Interval Definition and 677 Threads

  1. T

    Continuity implies boundedness in an interval proof

    Homework Statement If a function f is continuous at a point x, then f is bounded on some interval centered at x. That is, \exists M \geq 0 s.t. \forall y, if |x - y| < \delta, then |f(y)| \leq M Homework Equations The Attempt at a Solution Let \varepsilon > 0. Since f is continuous at x...
  2. G

    Interval notation and specifying units (v vs. t graph)

    Homework Statement #5 and #6 of the attached pdf on page 5 (graph on page 4 relates to said problems) Note: The professor did not cover how to do a problem like this, and the book does not have a similar problem, nor any other handouts. This definitely was a unique question. I'm unsure if I...
  3. Rasalhague

    Finding or estimating confidence interval for populaion mean

    From Koosis, I pieced together the following algorithm. Is sigma known? Yes? Then calculate the exact confidence interval using a normal distribution to estimate that of the sample means, with mean = the mean of sample means = the mean of the population, \mu_{\overline{x}}=\mu, and...
  4. S

    Finding for interval of m in quadratic equation.

    Maths Quadratic Question Homework Statement Find the interval in which 'm' lies so that the expression \frac{mx^2+3x-4}{-4x^2+3x+m} can take all real values ,where x is real. The Attempt at a Solution i have equated this equation to y y=\frac{mx^2+3x-4}{-4x^2+3x+m}...
  5. T

    Proving M_{0i} = 0 in Special Relativity

    http://books.google.com/books?id=qhDFuWbLlgQC&lpg=PP1&pg=PA11#v=onepage&q&f=false" Until he arrives at eq. 1.5 I don't understand the steps, can anyone explain it? thanks
  6. D

    Confidence interval for difference between means

    My course notes and textbook express this differently: To construct the confidence interval for diff. between means, Course notes (\bar{x1} - \bar{x2})\pmE Textbook (\bar{x1} - \bar{x2}) - E < \mu1 - \mu2 < (\bar{x1} - \bar{x2}) + E why the difference?
  7. M

    HELP how to prove (1-x^2)^n >= 1-nx^2 when x belongs to the interval [-1,1]?

    i got this question when i read the proof of stone-weierstrass theorem in baby rudin , page 159 , this inequality seems right when n becomes larger, since 1-nx^2 would be negative and (1-x^2)^n always positive, but i don't know how to proved it rigorously using binomial theorem for all n , or is...
  8. R

    Absolute Maximum and Minimum Values over a given interval

    Homework Statement Find the absolute maximum and absolute minimum values of the function (x^3)+(12x^2)-27x+9 on each of the following interval [-10,0] The Attempt at a Solution I got this and its saying its wrong. y'= (3x^2)+(24x)-27 factor: 3(x^2+8x-9) so x=-9 and x=-1 y''=6x+24...
  9. H

    Why is the Time component in the Space Time Interval negative?

    Why is the Time component in the Space Time Interval negative? The space time interval is defined to be: ds^2=dt^2-dx^2-dy^2-dz^2 or depending on the convention used it may also be: ds^2=-dt+dx^2+dy^2+dz^2 The equation is defining distance using the pythagorean theorem. This results...
  10. R

    Calculate the confidence interval (Statistics problem)

    I am trying to calculate the confidence interval for this problem using my T-84, and it's driving me mad because I'm so close to the correct answer. The problem is Homework Statement The answer to this problem is (22769.83, 30059.41) (This is an example problem.) When I try to duplicate...
  11. L

    Please, help me understand how these interval problems are solved

    Homework Statement simplify: 1. (-∞, -2) ∩ [-2, ∞) 2. (-∞, 5] ∩ [5, ∞) 3. (-∞, 5) U (4, ∞) 4. (-∞, 5) ∩ (3, ∞) Homework Equations The Attempt at a Solution It has been so long since I last saw a problem set like that. Honestly, I don't even remember how these...
  12. C

    How do I show that a derivative of a polynomial has a zero in an interval?

    Homework Statement If an even degree polynomial of order 2n intersects the x-axis twice, how do I show that the (2n-1) th derivative has a zero in that interval? Homework Equations example: let g(x)=x^3(1-x). Show without computation that g'''(c) =0 for some c in (0, 1). The...
  13. S

    Distance Traveled by Point in Time Interval [1,3]

    Homework Statement suppose the velocity of a point moving at time t, in seconds along a coordinate line is v(t)= (t+3)/(t^3+t) ft/sec. how far does the point travel during the time interval [1,3]. Homework Equations The Attempt at a Solution im not sure what to do, i used ∫3...
  14. T

    Power Series: Interval Of Convergence

    Homework Statement I am not really good with Series so I having a hard time with these problems. http://img835.imageshack.us/img835/858/img1257d.jpg Homework Equations The Attempt at a Solution The part I am stuck is where I highlighted. The first question: The whole thing is squared so I...
  15. A

    Probability over an interval in a Normal Distribution?

    Homework Statement In a photographic process, the developing time of prints may be looked upon as a random variable which is normally distributed with a mean of 16.28 seconds and a standard deviation of 0.12 second. Find the probability that it will take anywhere from 16.00 to 16.50 seconds...
  16. A

    Probability over an interval in a Normal Distribution?

    I've been given the question: In a photographic process, the developing time of prints may be looked upon as a random variable which is normally distributed with a mean of 16.28 seconds and a standard deviation of 0.12 second. Find the probability that it will take anywhere from 16.00 to 16.50...
  17. J

    Interval of Convergence and radicals

    Homework Statement Find the interval of convergence: \sum _{n=1}^{\infty } \frac{(-1)^n (x+2)^n}{3^n\sqrt{n}} Homework Equations The Attempt at a Solution \lim_{n\to \infty } |\frac{(x+2)^{n+1}}{3^{n+1}\sqrt{n+1}}*\frac{3^n\sqrt{n}}{(x+2)^n}| = \lim_{n\to \infty }...
  18. G

    Power series and the interval of convergence

    Homework Statement I need help finding the interval of convergence for f(x) = 3/(1-x^4). I think that the summation would be \Sigma 3 (x^4n) from n=0 to infinity, but I'm not sure how to get the interval of convergence. Homework Equations f(x) = 3/(1-x^4) The Attempt at a Solution...
  19. L

    Prediction interval, which brackets?

    Prediction interval, which brackets!? Hi, this is a quick question for a piece of statistics coursework I am doing. I have made a prediction interval with an upper bound of let's say 30 and lower of 20. I just don't know which brackets to use open or close e.g. (20,30) [20,30] (20,30]...
  20. K

    Spacetime Interval: Is it Invariant Under Rotations?

    I know that the spacetime interval is the same in coordinate system moving wrt each other at constant speed. But is it true that the spacetime interval is invariant under rotations? If so can you suggest a proof or post a link to one?
  21. F

    Is an Open Interval Homeomorphic to R?

    Hi, I am having a major brain fart. I realize that for example, open intervals and R are all topologically equivalent. Similarly, closed, bounded intervals are topologically equivalent And half open intervals and closed unbounded intervals are equivalent But I am having a...
  22. R

    Is the close interval A=[0,1] is compact?

    Is the close interval A=[0,1] is compact?
  23. G

    Which Differential Equation Has a Unique Solution on the Interval (0, pi)?

    Which of the following has a unique solution on the whole interval (0, pi)? y''+y=0, y(0)=0, y(pi)=0 y''+4y=0, y'(0)=0, y'(pi)=0 (t+1)y''+ty=0, y(1)=1, y'(1)=0 (t-1)y'+2y=0, y(0)=0, y'(0)=1 I'm not sure where to go on this one. I solved the first 2 equations and got: y=c*sin(t) and...
  24. L

    Determining the interval of convergence

    Homework Statement f(x)=x^{0.4} Construct a power series to represent the function and determine the first few coefficients. Then determine the interval of convergence. The Attempt at a Solution Determining the first few coefficients is simple enough. Take the first few...
  25. B

    Continuous on an open interval?

    Homework Statement Is t^2, -2t and 2 continuous on an open interval? Homework Equations I have re read the theorems and explanations of how something is continuous but i still don't understand it. The Attempt at a Solution
  26. K

    What Is the Interval of Convergence for the Given Series?

    Homework Statement The summation from n=1 to infinity of ((n!)x^(2n))/((2n-1)!) Find the Interval of Convergence of this series. Homework Equations Ratio test The Attempt at a Solution I applied the ratio test, then got x^2 times the limit as n approaches infinity of...
  27. S

    Finding the radius of convergence and interval of convergence

    Homework Statement This is the question of mine that I'm having a little confusion about. I know the whole process in which you use the ratio test to determine the radius of convergence and using that you test the end points of the summation to see if they converge at the end points aswell...
  28. M

    Power Series - Interval of Convergence Problem

    Homework Statement For which positive integers k is the following series convergent? (To enter - or , type -INFINITY or INFINITY.) Summation of n=1 to infinity of (n!)^2 / (kn)! Homework Equations ratio test: limit n-->infinity of [((n+1)!)^2/(kn+1)!] / [(n!)^2 / (kn)!] (have the...
  29. N

    How to calculate confidence interval not on t-table

    So as the title says. How do you calculate the confidence interval that is not on the t-table. For example how do you calculate the confidence interval for 97%? Assume that it is a normal distribution, you are not given σ and that n<30. Is there a formula? Or should i look for a more specific...
  30. K

    Help Convergence of Power Series, interval and radius of convergence question

    Homework Statement Determine the radius of convergence, the interval of convergence, and the sum of the series Summation from k=2 to ∞ of k(x-2)^k+1. Homework Equations ratio test? The Attempt at a Solution possibly take the derrivitive of the power series, then find the sum then integrate...
  31. S

    Power Series: Find Interval & Radius of Convergence

    Homework Statement \Sigma (from index k = 1 until infinity) Within the Sigma is the series : (k! * (x^k)) Homework Equations Ratio Test : lim as k approaches infinity |a(k+1) / ak| The Attempt at a Solution When I apply the ration test to the series and simplify I get lim k...
  32. P

    Ralphson-Newton Method And Interval Bisection

    I know quite well how to do these. However, most of the time, the starting points are just given to me i.e. the a and b values to starting iterating. I was just wondering if you were to find a starting point for x3-x-1 = 0, what would be the best starting point to use the Ralphson-Newton...
  33. T

    Which Equation for the Space-Time Interval Should You Use?

    I have two questions about the space-time interval question. I'm doing a little research about space time, and about space time intervals, but I'm not sure which equation to take. Some sources say that its s^2 = x^2 - c^2 t^2, other say its s^2 =c^2 t^2 - x^2. So which one do I take? The...
  34. B

    Is the Open Cover of the Interval [0,1) with Infinite Subcovers Effective?

    Given the interval [0,1) is this a good Open cover with infinite subcovers {(An)} such that An =(-1/n, n) with n \in lN Is there any reason we should stay to the boundaries of the set we're trying to cover? I'm thinking that even (-n, n) should work. Am I wrong?
  35. C

    Finding the Radius & Interval of Convergence of a Power Series

    Homework Statement \sum from n=1 to inf (1+ 1/2 + ... 1/n)x^n Find the radius of convergence and the interval of convergence of the given power series. Homework Equations Dunno.. The Attempt at a Solution Stuck thinking about it. I'm not sure if I can combine what's in brackets with the...
  36. S

    What is the frequency of note y if it is two sext higher than note x?

    Homework Statement Given that note x has frequency 300 Hz. Find the frequency of note y if it is two sext higher than x. Homework Equations sext interval --> x : y = 24 : 40 The Attempt at a Solution I can find the value of y if the interval is sext. x : y = 24 : 40 300 : y =...
  37. J

    Determine the interval validity of this separable equation

    Homework Statement Find the solution of the given initial value problem in explicit form and determine the interval in which the solution is defined. \[x dx+ye^{-x}dy = 0\] with initial condition y(0) = 1 Homework Equations The Attempt at a Solution I solved the first part...
  38. maverick_starstrider

    Derivation of space-time interval WITHOUT Lorentz transform?

    Hi, I'm reading a book on SR/Field theories that simply posits the space-time interval and from that defines a Lorentz transform as any transformation which leaves the interval invariant. My question is how do we posit the space-time interval in this manner using only the postulates of...
  39. M

    Integrals of differentialble functions on a bounded interval

    Given two functions f_{1}(x) and f_{2}(x) that are differentiable on [a_{1},a_{2}] and \int^{a_2}_{a_1}f_1(x)f'_{2}(x)dx=b_2, how would one calculate \int^{a_2}_{a_1}f_1(x)f'_{2}(x)dx? This is not a homework problem. I saw it on the internet and realized that I did not know where to begin...
  40. P

    Spacetime Interval Relativity question.

    Homework Statement Two events occur 5 s apart in time and 3 s apart in space. A clock traveling at a speed of .6 can be present at both these events. What time interval will such a clock measure between the events? A. 8 s B. 5.8 s C. 5 s D. 4 s E. 2 s F. Other Homework Equations...
  41. G

    Integration on a open interval?

    Homework Statement I was wondering how one integrates on a open interval. For example let's say I wanted to integrate the function f(x) = x^2 + 2x + 3 on (2,7). Note that it's on the OPEN INTERVAL not closed of all the x values from 2 to 7 not including 2 to 7. I'm not trying to integrate...
  42. M

    Use IVT to show that f(x) exists on interval (0,1)

    Homework Statement Using IVT, show that 3(\cos(\pi x)) - 3x + 1 exists on interval (0,1) Homework Equations None The Attempt at a Solution I think I got the right idea, but on my quiz (this was a question I just had on a quiz) I didn't know if I was finished or not. So when using 0 on the...
  43. I

    Average Velocity of a particle moving in a circle over a given interval

    Homework Statement Homework Equations d = 2.5 c = pi*d = 7.854 velocity/s ?= c * 2 = 15.7079The Attempt at a Solution Since PR is 1/4 of the circle and the particle moves around the circle 2 times per second, I thought the average velocity would be 1/8th of the velocity that it's traveling...
  44. C

    Interval of Convergence for a Series

    Homework Statement Ok, so I don't need help with this part, I just got stuck at the following step when attempting to find the interval of convergence: The Attempt at a Solution I got here: -4 < x^2 < 4 So, I need to solve this inequality. But can I? How can I take the square root...
  45. A

    Sampling Interval for Data: Calculating Omega and Number of Samples Per Period

    I have been given a data and asked to state the sampling interval Heres what I know The data has a value generated for each month of the year, I have calculated a period of 11 years. Now I know the formula: 2PI/omega = number of samples per period So will Omega = PI/66
  46. T

    Comparison Test on Interval 0 to 1

    Homework Statement Determine whether or not the integral from 0 to 1 of (5ln(x)) / ( x^(3/2) ) converges or not. Homework Equations The Attempt at a Solution I just need to know which end of the integral they are talking about. As x=>0, y=>-infinity. As x=>1, y=>1. I'm assuming...
  47. H

    Power Series Interval of Convergence

    Homework Statement I need a power series with a radius = pi. (So when you do the ratio test on this power series you get pi) Homework Equations The Attempt at a Solution I tried x^n*sin(n) and thought of stuff like that but couldn't come up with a working power series
  48. S

    The Proof: There exist interval [A,B] that cannot have a sub-interval

    This is a proof that: There exist interval [A,B] on the real numbers line that is indivisible as a mathematical point is indivisible. ------------------------------ Its a proof by contradiction, starting with premise 1 Proof \aleph L represents the cardinality of all possible...
  49. A

    Interval Bisection: Solve for Root in [1, 2]

    Homework Statement Hi Please, I need clarification on this queston Show that the equation 0 = x/2 -1/x ,x>0, has a root in the interval [1, 2]. b Obtain the root, using interval bisection two times. Give your answer to two significant figures. Homework Equations Change in...
  50. H

    Increasing and decreasing function in certain interval

    Homework Statement P(x) is an increasing function and Q(x) is a decreasing function in interval a ≤x≤b, x is positive. P(x) and Q(x) are located in 1st quadrant. Another function γ(x) satisfies m≤γ(x)≤M. Find the value of m and M if: a. γ(x) = P(x) - Q(x) b. γ(x) = P(x) . Q(x) c. γ(x) =...
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