Geometric Definition and 813 Threads

  1. G

    Calculus II - Infinite Series - Geometric Series

    Homework Statement Hi, I'm trying to solve the problem in the attachment. I was asked to evaluate the left hand side equation of the equal sign. I was unsure how to go about evaluating it so I consulted my solutions manual to look up the first step. The right hand side equation of the...
  2. O

    Sum to Infinity of a Geometric Series

    Homework Statement Q. Find the range of values of x for which the sum to infinity exists for each of these series: (i) 1 + \frac{1}{x} + \frac{1}{x^2} + \frac{1}{x^3} + ... (ii) \frac{1}{3} + \frac{2x}{9} + \frac{4x^2}{27} + \frac{8x^3}{81} + ... Homework Equations S\infty =...
  3. O

    Sum to Infinity of a Geometric Series

    Homework Statement Q. Find, in terms of x, the sum to infinity of the series... 1 + (\frac{2x}{x + 1}) + (\frac{2x}{x + 1})^2 + ... Homework Equations S\infty = \frac{a}{1 - r} The Attempt at a Solution S\infty = \frac{a}{1 - r} a = 1 r = U2/ U1 = (\frac{2x}{x + 1})/ 1...
  4. O

    Sum to Infinity of a Geometric Series problem

    Homework Statement Q.: A geometric series has first term a and common ratio r. Its sum to infinity is 12. The sum to infinity of the squares of the terms of this geometric series is 48. Find the values of a and r. Ans.: From textbook: a = 6, r = 1/ 2 Homework Equations...
  5. Telemachus

    Finding the Curve that Satisfies a Geometric ODE

    Hi there. I have this exercise in my practice for differential equations, and it asks me to find the curve that satisfice for every point (on the xy plane) the distance from (x,y) to the points of intersection for the tangent line and the x axis, and the normal with the x-axis remains constant...
  6. N

    There are 10 terms in the geometric progression.

    Homework Statement 3,6,12...1536 determine the number of terms in the progression Homework Equations The Attempt at a Solution a=3 r=2 n= ar^n-1 1536= (3) (2)^n-1
  7. S

    What Focal Length is Needed to Project a 35mm Slide onto a Large Screen?

    Homework Statement A 35mm slide(picture size is actually 24 by 36 mm)is to be projected on a screen1.80m by 2.70 m placed 7.50m from the projector. What focal length lens should be used if the image is to cover the screen?Homework Equations the only equation i can think of is the lens equation...
  8. Z

    Riemann-Stieltjes Integral geometric intepretation

    Hi all, I would like to ask for the geometric interpretation of the riemann-stieltjies integral. Suppose we have an integral, (integrate f dg) over the interval [a,b], where g is monotonically increasing. Can i interpret it as the area between f and the g function? Moreover, i am a...
  9. T

    Using Power-of-a-Point Theorem in Geometric Proofs

    Homework Statement Point A is on a circle whose center is O, AB is a tangent to the circle, AB = 6, D is inside of the circle, OD = 2, DB intersects the circle at C, and BC = DC = 3. Find the radius of the circle. Homework Equations Power of a point theorem (several cases found online...
  10. T

    Geometric shape of Minkowski space

    So, suppose for visualization there are only two dimensions: ct and x. Now if the metric where Euclidean, we could visualize this space is a simple plane. What would be the shape of the "plane" when the metric is +1, -1 (Minkowski)? Is it somehow hyperbolic?
  11. J

    Exploring the Geometric Motivation Behind the k-Dimensional Volume Function

    I have a quick question. First let me give a definition. Let a_1, a_2, ..., a_k be independent vectors in R^n. We define the k-dimensional parallelopiped \mathbb{P}(a_1, ..., a_k) to be the set of all x in R^n such that x = c_1a_1 + \cdots + c_k a_k for scalars c_i such that 0 <= c_i...
  12. H

    Question About Geometric Sequence.

    i know how the basic geometric sequence system works, but what if i want to subtract a fixed amount every For example if i start with $5000 (a1) and is multiplied by 1.05 (5% / r) every day for 20 days (n) I would have $13,267. But what would I have if $20 dollars was subtracted from the...
  13. U

    Topology question → What geometric figure?

    James came to a place where there was a bridge, supported by parabolic arcs. In the middle waving a transparent gelatinous substance in the form of spherical shell of exotic matter. He had come to " delighted well", a horizontal formation, which is much talk and little experienced. Slowly James...
  14. M

    Solving Geometric Progression: Sum of h(1 + 3^h + 3^2h + ... + 3^(n-1)h)

    Homework Statement This isn't the whole question, I understand the prior parts but somehow stuck on the "easy" part :( Need to solve a geometric progession problem.. find the sum of: h(1 + 3^h + 3^2h + ... + 3^(n-1)h) Where nh = 1 The sum should equal to (2h)/((3^h) -1) which is...
  15. A

    Vectors and how to find the planes to express geometric conditions

    Homework Statement The normal vector of each of the following planes is determined from the coefficients of the x-, y-, z- terms. pi1: a1x+b1y + c1z + d1=0 pi2: a2x+b2y+c2z+d2=0 pi3: a3x+b3y+c3z+d3=0 Define the extended vector for each plan as follows: e1= [a1, b1, c1, d1] e2= [a2, b2, c2...
  16. Femme_physics

    Geometric Series: Find 3 Numbers for 5 Components

    Homework Statement You must enter 3 numbers between 31 and 496 so there will be an increasing geometric series with 5 components. The Attempt at a Solution It tells me I'm off. That q=2. But how? http://img716.imageshack.us/img716/8895/300xk.jpg
  17. C

    Geometric series partial sums question

    I am looking at a geometric series problem that has already been worked out, so not assigned, but I do not see where they get a number: Summation from n=1 to inf: 1/(n^2+4n+3) In doing the partial sums, he has (1/2)* summation... 1/(i+1) - 1/(i+3) I understand the breakup, but where does...
  18. S

    Infinite geometric series application (long)

    Homework Statement Assume that the drug administered intravenously so the concentration of drug in the bloodstream jumps almost immediately to its highest level. The concentration of the drug decays exponentially. A doctor prescribes a 240 milligram (mg), pain-reducing drug to a patient who...
  19. Femme_physics

    Finding the Missing Number in Geometric Series

    Homework Statement http://img833.imageshack.us/img833/681/a1a2.jpg Calculate which number you have to add to a1, a2 and a3 in order to get 3 subsequent numbers in a geometric series The Attempt at a Solution Getting a2 and a3 was easy. Plugging in the values I need for n, I get...
  20. D

    Probability theory - Poisson and Geometric Random Variable questions

    Homework Statement [/b] There are two problems I need help with, which are posted below. Any help is appreciated. 1)Let X have a Poisson distribution with parameter λ. If we know that P(X = 1|X ≤ 1) = 0.8, then what is the expectation and variance of X? 2)A random variable X is a sum of...
  21. J

    Geometric Sequence: Find 4th Bounce | Get Steps

    A ball is dropped from a height of 3 ft. The elasticity of the ball is such that it always bounces up one-third the distance it has fallen. (a) Find the total distance the ball has traveled at the instant it hits the ground the fourth time. (Enter your answer as an improper fraction.) Can...
  22. S

    Geometric interpretation of \int x f'(x)

    I was reading Tom Apostol's expostion of Euler's Summation Formula ( http://www.jstor.org/pss/2589145) and it occurred to me that it would be convenient to visualize \int_a^b x f'(x) geometrically. In that article, it arises from integration by parts: \int_a^b f(x) dx = |_a^b x f(x)...
  23. I

    Solving Geometric Progression & Logarithmic Equations Math Questions

    I'm stuck on these three maths questions. 1) In a geometric progression, the sum to infinity is four times the first term. (i) Show that the common ratio is 3 (ii) Given that the third term is 9, find the first term. (iii) Find the sum of the first twenty terms. 2) Solve the...
  24. B

    Bit confused about the geometric series

    I'm confused about the sum of the geometric series: \sum ar^{n-1} = \frac{a}{1-r} when |r|<1 but if you have a series like: \sum (1/4)^{n-1} the sum is: \frac{1/4}{1-(1/4)} should't it be \frac{1}{1-(1/4)} because there is no a value?
  25. J

    Understanding the Meaning of (e1^e2)\cdote3 in Geometric Algebra

    What is the meaning of (e1^e2)\cdote3? (outer product multiplied by inner product)
  26. T

    Proving Geometric Fact: u+v Perpendicular to u-v Using Dot Product

    "If u and v are any two vectors of the same length, use the dot product to show that u + v is perpendicular to u − v. What fact from geometry is does this represent." This is basically the last question in an assignment on vectors (first year university, linear algebra). The questions all focus...
  27. J

    Geometric Progression: Finding the Outstanding Loan Amount after Each Year

    Question: John took a bank loan of $200000 to buy a flat. The bank charges an anual interest rate of 3% on the outstanding loan at the end of each year. John pays $1000 at the beginning of each month until he finishes paying for his loan. Let Un denote the amount owed by john at the end of the...
  28. L

    Convergence of a geometric series; rewriting a series in the form ar^(n-1)

    Homework Statement Determine whether the geometric series is convergent or divergent. If it is convergent, find its sum. \sumn=1infinity (-3)n-1/4nHomework Equations A geometric series, \sumn=1infinity arn-1=a + ar + ar2 + ... is convergent if |r|< 1 and its sum is \sumn=1infinity arn-1 =...
  29. ThomasMagnus

    Solve Geometric Sequence Word Problem in Gossipopolis

    I'm having trouble with a word problem: The people of Gossipopolis cannot keep a secret. Upon being told a secret, a person from Gossipopolis will spend the next hour telling three people. In turn, those friends will spend the next hour each telling 3 more people. This process continues and...
  30. P

    Change of Basis + Geometric, Algebraic Multiplicities

    Making a change of basis in the matrix representation of a linear operator will not change the eigenvalues of that linear operator, but could making such a change of basis affect the geometric multiplicities of those eigenvalues? I'm thinking that the answer is "no", it cannot.. Since if...
  31. C

    What is the geometric multiplicity of \lambda=0 as an eigenvalue of A?

    Homework Statement \lambda=0 is an eigenvalue of A= |1 1 1 1 1| |1 1 1 1 1| |1 1 1 1 1| |1 1 1 1 1| |1 1 1 1 1| Homework Equations Find the geometric multiplicity of \lambda=0 as an eigenvalue of A The Attempt at a Solution I row reduced it then got the last four rows of all 0s...
  32. C

    The geometric mutiplicity of a matrix

    It is a 5x5 matrix with 1s in all of its entries. Find the geometric multiplicity of \lambda=0 as an eigenvalue of the matrix.
  33. C

    The geometric mutiplicity of a matrix

    Homework Statement It is a 5x5 matrix with 1s in all of its entries. Homework Equations Find the geometric multiplicity of \lambda=0 as an eigenvalue of the matrix. The Attempt at a Solution WHat i did was use the characteristic equation of A-\lambdaI and then row reduce it...
  34. ThomasMagnus

    Calculating Levels in a Geometric Series Phone Tree

    A school phone tree has 1 person responsible for contacting 3 people. If there are 1500 students in the school, how many levels will there be on the phone tree (assuming 1 person is at the top of the tree)? My Solution: This question forms a geometric series: A(first term)=1 R(common...
  35. ThomasMagnus

    Geometric Sequence: T1=0.1024, T2=0.256, Middle Term=156.25

    A finite geometric sequence has t1 = 0.1024 and t2 = 0.256. How many terms does this sequence have if its middle term has a value of 156.25? My Solution Common Ratio: T2/T1=(.256)/(.1024)=2.5 What term # is the middle term? tn=ar^n-1 a=0.1024 r=2.5 tn=156.25...
  36. D

    Find Equivalent Resistance Across Rab: A Geometric Conundrum

    Homework Statement Find the equivalent resistance across Rab Homework Equations Series: Req=R1+R2...Rn Parallel Req=(R1 * R2 *...Rn) / (R1 + R2 +...Rn) The Attempt at a Solution its the geometry that is throwing me off in this problem. Starting on the left side, I want to put...
  37. K

    Geometric proof: minimum angle to point in a line segment

    Hi, I have a problem I need to solve for a piece of software I'm writing, and I think I've got it but it would be great if somebody could take a quick look at this proof and see if I've overlooked anything. Thanks in advance. Here is the problem: We're working in R_3 here. Given a line...
  38. JeremyEbert

    Geometric construction of the square root

    Is anyone familiar with this method of determining square roots? http://www.cs.cas.cz/portal/AlgoMath/Geometry/PlaneGeometry/GeometricConstructions/SquareSquareRootConstruction.htm I have an equation that I'm working on that expands on this a bit and I'd love some feedback.
  39. R

    Construct geometric line with nested root

    well it is easy to construct sqrt(2) with a triangle with two sides of length 1. but what about sqrt(2 + sqrt(2)) or the iteration sqrt(2 + sqrt(2 + sqrt(2))). the question is how to construct a line with length sqrt(sqrt(2)) i guess(beginning with lines of length 1), but i am not sure.
  40. A

    Geometric sequences and Fibbonacci Numbers

    Homework Statement A) In a certain geometric sequence every term is the sum of the two preceding terms, viz. the Fibonacci sequence, what can be said about the common ratio of the sequence? So how do I go from 1,1,2,3,5,8,13,21,34... to (1+/-sqrt(5))/2? Then find numbers A and B such (for...
  41. F

    Find Geometric Structures with Software

    Hi! Do you know if there are softwares where you can put in numbers and it tries to find a geometric structure that fits them? Like 1,2 and 5 becomes a triangle. Thank you!
  42. G

    Geometric Progression nth Term: Formula and Working Example

    just a check of my work please. I have to write an expression for the nth term of this geometric sequence. a1=100 a2=106 a3=112.36 I've worked out the ratio to be r=1.06 I am using the formula un=ar(n-1) so the expression i have come up with is un=100(1.06)(n-1) Is this correct? I have...
  43. J

    Geometric Distribution Question

    Homework Statement An experiment consistion of tossing three fair coins is performed repeatedly and "success" is when all three show a head. What is the probability that the success is on the third performance of the experiment? Homework Equations Geometric distribution equation p(x) =...
  44. S

    Exploring Geometric Meaning of Time and Space at a Black Hole's Event Horizon

    hello, what does exactly mean geometrically that time and space switch roles at the event horizon of a nonrotating black hole?. I understand that the - for time becomes a + and the + for space becomes -, but how to interpret it geometrically? also I want to know if after the event horizon...
  45. Char. Limit

    What is the geometric significance of curl in vector fields?

    Homework Statement OK, so I understand how to calculate this stuff. But I want to know the geometric significance of a line integral over a vector field, a double integral over a vector field, and of course curl. Homework Equations \int_C \vec{F} \cdot d\vec{r} \int \int_C \vec{F}...
  46. N

    Solving Linear Equations in Two Variables with Geometric Sequences

    Note: I didn't use the template because I feel it did not fit the question well enough. This is concerning a system of linear equations in two variables where its constants in " ax+by=c " form show a geometric sequence, i.e. " nx + any = a2n ". Another way of putting this is " y=(-1/a)x + a...
  47. F

    Trying to get some geometric intuition on differential equations

    I want to preface this by saying that these questions are not to find an exact answer, just to build intuition. If you find them ill-posed or incorrect, it would be most helpful if you could show me a "better way" of looking at it. So, I'm trying to gather a geometric viewpoint of...
  48. A

    Geometric Series Homework: Sum of ((n+1)*3^n)/2^(2n)

    Homework Statement The sum of ((n+1)*3^n)/(2^2n) Homework Equations absolute value of r must be less than 1 for the series to be convergent. The Attempt at a Solution i tried multiplying it out and splitting it up like: 3^n*n/(2^(2n))+3^n/(2^(2n)) but then i am stuck when I...
  49. jegues

    Taylor series using Geometric Series

    Let f(x) = \frac{4-4x}{4x^{2} -8x -5}; given the partial decomposition, \frac{4-4x}{4x^{2} -8x -5} = \frac{1}{5-2x} - \frac{1}{1+2x}, find the Taylor series of f(x) about 1. Express your answer in sigma notation and simplify as much as possible. Dtermine the open interval of...
  50. B

    Geometric Example of Torsion Cycles and Relative Cycles (in Homology)

    Hi, Everybody: I am trying to understand torsion and relative cycles in a more geometric way; I think I understand some of the machinery behind relative cycles (i.e., the LES, and the induced maps.), and I understand that by ,e .g., Poincare duality, in order to have torsion in...
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