Points Definition and 1000 Threads

  1. C

    Probability that n points lie on one side of a circle

    Homework Statement Suppose that n points are independently chosen at random on the circumference of a circle and we want the probability that they all lie in some semicircle. Let ##P_1...P_n## denote the n points. Let A denote the event that all the points are contained in some semicircle and...
  2. J

    Fourier series of functions with points of discontinuity

    If you have a function with countable discontinuities on an interval, I know that the Fourier series will converge to that function without those discontinuities. But how could you explain that formally? If the basis of the Fourier series span the space L^2[a,b], that would include functions...
  3. D

    Model the relationship between 3d points given two reference points

    Homework Statement Trying to figure out how to model the relationship between two 3D points, A and B. Both points have visibility to 2 common reference points, C and D. Bearing and angle readings are available from both A and B to the reference points C and D. The reference points C and D are...
  4. H

    Linear approximation given accuracy points

    Homework Statement Use a graphing calculator or computer to verify the given linear approximation at a = 0. Then determine the values of x for which the linear approximation is accurate to within 0.1. (Round the answers to two decimal places.) tan(x) ≈ x Homework Equations derivative...
  5. turbo

    Humans were using stone spear points over 1/2M years ago

    Probably can't teach about this in the Bible belt... http://www.google.com/hostednews/afp/article/ALeqM5hISS_RrQOpDbJ9sk84ActLvv-6ZA?docId=CNG.9484301c0f281a31e8383bf96341f10b.471
  6. H

    Finding Collinear Points Given 1 point and 2 lines

    Hello - I need help finding collinear points: Given: Equations of 2 lines, L1 and L2 1 points, P3 Want to find points P1 and P2 that lie on L1 and L2 respectively that are collinear to P3. I know that there can be multiple combinations of points P1 and P2 so to narrow down the list...
  7. C

    Create 3d function with a set of points

    I'm creating a computer program and I need to see what's most efficient. I need another program [lol] that I can input 3d points in and have it create the function. the points are this v e t 100 500 3...
  8. E

    Branch points and cuts of multivalued function

    Homework Statement This problem is on how to identify the branch points and the branch cuts of a multivalued function. Consider the following function f(z)=Log(1+z^\alpha) where \alpha is a rational number and z\in \mathcal{C}.Homework Equations Obviously, for the function z^\alpha, it has...
  9. B

    Help with finding first derivative and critical points?

    Homework Statement What are the critical points of function f(x) = 2 (x^2 + 4)^(1/2) - 4x + 24 ?Homework Equations When f'(x) equals 0 or is undefined, x is a critical number.The Attempt at a Solution The original function is f(x) = 2 (x^2 + 4)^(1/2) - 4x + 24 . I got the derivative as f'(x) =...
  10. S

    Algebra: If P(x), degree n, shares n points with x^n, then it is x^n

    Homework Statement Prove that if a Polynomial P(x) of degree n, shares n points with xn, then P(x)=xn. (a more general proof would be almost the same but for two polynomials, but I think I've proved this if this is proved)Homework Equations (FTA) Fundamental Theorem of Algebra - Every P(x) of...
  11. M

    Lagrange multipliers and combinations of points

    I was wondering how they got all the different combinations of points? Why can't they just put (+-√2,+-1,+-√(2/3)) ?
  12. Q

    Plane equation given two points and distance to parallel line

    Homework Statement Find the plane through the points P = (1, 1, −1) and Q = (2, 1, 1) and parallel to a line r {(1, 0, 2) + t(1, 0, 2), t ∈ R} with distance 1 to the plane Homework Equations A=(a1,a2,a3),B(b1,b2,b3),A and B are vectors. AxB= det[i j k;a1 a2 a3;b1 b2 b3] ";" means change of...
  13. O

    Understanding displacements of points by interpreting directions

    Suppose that points x and y are given in Euclidean space. Point x is displaced to point x1 by x1=x+a(x-y) Given that a is positive number, how can it be shown that the distance x1 to y is larger than distance x to y. I'm mainly interested in a vector interpretation of the above update...
  14. K

    Find Intervals, where Function is Convex or Concave and Inflection Points

    Homework Statement y= (x^2 -7) e^xThe Attempt at a Solution I'm trying to find inflection points by setting the second derivative=0 I found that the derivative is: ##2xe^{x}+x^{2}e^{x}-7e^{x}=0## ##e^{x}[2x+x^{2}-7]=0## Then, the 2nd derivative: ##e^{x}[(x-1)(x+5)]=0##, then the inflection...
  15. J

    Finding speed of roller coaster at different points

    Homework Statement Homework Equations KE= 1/2 m v2 PE = mgy The Attempt at a Solution I'm not sure how to start this because there is no given mass. If I use a kinematics equation I don't have an acceleration.
  16. E

    Integration with branch cuts and singular points

    Homework Statement Prove that \int_0^{\infty} \frac{x^{1/\alpha}}{x^2-a^2} dx = \frac{\pi}{2a}\frac{a^{1/\alpha}}{\sin(\pi/a)}\left(1-\cos(\pi/\alpha)\right) where a>0 and -1<1/\alpha<1 Homework Equations It is apparent that there are two first order singular points at x=a and x=-a...
  17. U

    Uniform grid of points on a sphere

    How can one create a uniform solid-angular distribution of vectors in 3D space from a common origin, or in other words a grid of points on the surface of a sphere wherein the points are equidistant from each other? Spherical polar coordinates/the latitude-longitude scheme is obviously not the...
  18. A

    Verify whether the following points are optimal solutions to the LP?

    Homework Statement Points (4,4) and (2,0) Minimise 3x1+6x2 s.t. 6x1-3x2=12 x1,x2>=0 Homework Equations The Attempt at a Solution I tried solving this the way LP questions are solved in general, graphically. So I drew a graph plotting the objective and the constraint...
  19. D

    Are All Inflection Points Also Critical Points?

    Are inflection points critical points? and what about at the value that f(x) undefined? Is that critical point too?
  20. F

    Lattice Points on Circle: Determining the Number of Points on the Boundary

    Does any circle having irrational radius have no lattice points on its boundary ? Extended question: Is there any way to determine the number of lattice points lying on the boundary of a given circle ? *The centres of these circles are all (0,0) *
  21. D

    Minimizing distances between points of curves

    PROBLEM STATEMENT: I'm looking for a somewhat general method to find the expression for the distance (in \R^2 mortal, euclidean space) between a point in a certain curve and some point outside the line. ATTEMPTS TO SOLVE THE PROBLEM: In the case of the distance between the origin and some...
  22. R

    Classify the equlibrium points of the system-Pls help me, its

    Classify the equlibrium points of the system-Pls help me, its urgent! Hi , I have my maths exam tomorow and I am not able to understand the concept to classify the equilibrium points of a system.. I will be grateful if anyone could help me with this problem Classify the equilibrium points...
  23. T

    Find y' if (x-y)/(x+y)=(x/y)+1 and show that there are no points on that curve

    Homework Statement Use implicit differentiation to find y' if (x-y)/(x+y)=(x/y)+1. Now show that there are, in fact, no points on that curve, so the derivative you calculated is meaningless. Homework Equations The Attempt at a Solution I managed to get it into the form: dy/dx =...
  24. S

    Difficulty with accumulations points

    Homework Statement Hi guys, I'm having real difficulty with understanding accumulation points. I don' really know why that is since others seem to understand the concept fine but I'm very lost. For example, I'm practicing some questions and one of the is : If S is the set of rational...
  25. B

    Focal Points in Optics: Real-World Applications

    Hello everyone, I'm an optometry student who is currently doing Optics 1, and I have a general question about focal points. I can do the math regarding F1, F2, and the nodal ray, and I am decent at drawing the ray traces, but I would like to know more about the actual real world applications...
  26. D

    MHB Finding Fixed Points for F, B, A

    Is there a clean may to get the fixed points for \begin{alignat*}{9} F - 2B' - cB - \frac{3}{4}AB^2 - \frac{3}{4}A^3 & = & 0 & \quad & \Rightarrow & \quad & B' & = & \frac{1}{2}F - \frac{c}{2}B - \frac{3}{8}AB^2 - \frac{3}{8}A^3\\ 2A' + cA - \frac{3}{4}A^2B - \frac{3}{4}B^3 & = & 0 & \quad &...
  27. O

    Weighted average of arbitrary k points from a line

    Suppose a set of k arbitrary points, x_i, 1<=i<=k, x_i from R^2 are selected from a line. How can it be shown that a weighted barycenter x_o=(o_i*x_i)/(o_1+o_2+...+o_k) also belongs to that line (assume o_i are arbitrary weights)? Does the choice of weights restrict the solutions (ie, a...
  28. P

    Finding the points of intersection of two ellipses

    Does anyone know where I can find an algorithm for the points of intersection of two ellipses existing with arbitrary center points and rotations and having 0, 1, 2, 3 or 4 points of intersection?
  29. T

    Find the points on a graph at which the tangent line is parallel

    Homework Statement Find the points on the graph y=x^3/2 - x^1/2 at which the tangent line is parallel to y-x=3. Homework Equations The Attempt at a Solution First I found that the derivative of y=x^3/2 - x^1/2 is 1x. I then rewrote the other line as y = 3+x and found the...
  30. Nero26

    Test for coplanarity of four points

    Hi all, If a,b,c,d are position vectors of four points A,B,C,D.The points will be coplanar if xa+yb+zc+td=0,x+y+z+t=0,provided x,y,z,t are not all 0,and they are scalars.Is this test needed to show 4 points are coplanar? If we consider two lines joining A,B and C,D then this will give us two...
  31. C

    Parametric Equations, Solve for Points of Intersection

    y=x^5 x=y(y-1)^2 find points of intersect correct to 1 decimal point
  32. D

    Lebesgue outer measure of a set of countably many points is 0 - logic check

    So I know that the Lebesgue outer measure of a set of only countably many points is 0. An example of this is the rationals as a subset of the reals.I want to make sure my intuition behind this is correct. The process: Now, if we are going to take the Lebesgue outer measure of the rationals, we...
  33. S

    Maple How can I fit a sigmoid line to data points using Excel or Maple?

    Hi I used plot digitizer software to pull data points off a picture of a graph and i need to fit a line to the points (and get an equation for the line). I know the data points fit to an s-curve from the picture. I'm thinking excel doesn't do this, or maybe I missed it? I have access to maple...
  34. W

    Critical Points & their Nature of a Multivariable Function

    Homework Statement f(x,y) = xy(9x^2 + 3y^2 -16) Find the critical points of the function and their nature (local maximum, local minimum or saddle) Homework Equations The Attempt at a Solution I have partially differentiated the equation into: fx = 27yx^2* + 3y^3 -16y fy =...
  35. A

    Tricky problem worth 2 points on my final grade

    Tricky problem worth 2 points on my final grade :) Homework Statement Homework Equations I honestly don't know how to tackle this. I think it's going to contain ƩF=mg, and some basic kinematic equations. The Attempt at a Solution Where do is start?
  36. O

    MHB Limit Points of Unbounded Interval

    Hello everyone! I'm trying to prove that the closure of $A = [-\infty,0)$ is $[-\infty,0]$. So far, I have proved that all points in $[-\infty, 0)$ are limit points of A, then I have proved that $\sup A = 0$, so it is in the closure, so $[-\infty, 0]$ subsets the closure. But how do I know...
  37. N

    Probability - Independent events with minimal points in sample space

    Homework Statement What is the minimum number of points a sample space must contain in order that there exists n independent events A_1, ..., A_n , none of which has probability zero or one? Homework Equations None at this time The Attempt at a Solution I was thinking that if each A_i...
  38. V

    Points in 3D space (Related to Calculus)

    The equation for the number of possible connections between n points on a 2D plane is (n-1)*(n/2). What is the equation for the number of possible connections between n points on a 3D plane? Is it the intregal of (n-1)*(n/2)?
  39. U

    Number of points having integral coordinates

    Homework Statement Let A,B,C be three sets of complex numbers as defined below A = {z:|z+1|\leq2+Re(z)}, B = {z:|z-1|\geq1} and C=\left\{z: \frac{|z-1|}{|z+1|}\geq 1 \right\} The number of point(s) having integral coordinates in the region A \cap B \cap C is Homework Equations...
  40. D

    Mathematica Fitting Curve to Data Points using Mathematica

    I am trying to use Mathematica to fit a curve to these data points ListPlot[{{2*Pi/(1 - 0^2/16), 5 (3 - Log[2])}, {2*Pi/(1 - .05^2/16), 10 (3 - Log[2])}, {2*Pi/(1 - .1^2/16), 15 (3 - Log[2])}, {2*Pi/(1 - .15^2/16), 20 (3 - Log[2])}, {2*Pi/(1 - .2^2/16), 25 (3 - Log[2])}...
  41. O

    MHB Bounded Set with Two Limit Points

    Hello everyone! I'm asked to find a set that is bounded and that has exactly two limit points, now this is how I am thinking. Consider the set $A_n = [0,\frac{1}{n}) \cup(2-\frac{1}{n},2]$, if $A_1 = [0,1)\cup(1,2]$, $A_2=[0,1/2)\cup (3/2,2]$. If I let $n$ grow indefinitely, I will have only...
  42. A

    Local Max/Min and saddle points

    Homework Statement Find the local max/min or saddle points of f(x,y) = (x-y)(1-xy) Homework Equations The Attempt at a Solution I expanded the equation to f(x,y) = x-y-(x^2)y+xy^2. Then I found the partial derivatives of the function. fx = 1-2xy +y^2 fy = -x^2-2xy I'm...
  43. C

    Determining the second order polynomial from the intersection points

    Homework Statement Let's say that we have a second order polynomial function, and we know all of the points where it intersects with the x and y axis. Ex: (-2; 0), (0; 2), (1; 0) How does on determine the ax^2+bx+c polynomial form based on that? Homework Equations - The Attempt at...
  44. J

    Find the points of discontinuity: f(x) = x + 1 , for x < 1 and 1/x for x ≥ 1?

    Find the points of discontinuity: f(x) = x + 1 , for x < 1 and 1/x for x ≥ 1? ^ supposed to be a piece-wise function. State whether f is left- or right-continuous at each point of discontinuity. I'm having difficulty figuring this out... please help?
  45. Y

    Sup and inf of a set of limit points

    Homework Statement I have to prove that the supremum and infimum of a set of limit points of a a sequence {an} are themselves limit points. Homework Equations The Attempt at a Solution I have been messing around with definitions but have not made any progress. Please help...
  46. R

    Set A is open relative to Y iff A also contains points of a set B open in X?

    Problem: I'm trying to make sure i understand the following proof: Suppose we have the metric spaces (X, d) and (Y, d) with Y < X. Then A is open in Y \Leftrightarrow A = B \bigcap Y where B is an open set in X. Here is the proof I have written down: (\Rightarrow) - Assume A...
  47. T

    Why Did I Get the Wrong Answer for the Force at Point C?

    Homework Statement Here is the question along with part of the solution. I am online concerned about finding the force at C. The Attempt at a Solution For my solution I decided I would sum the moments about point B. However I ended up getting the wrong answer for the force at...
  48. S

    Points Nearest/Farthest from Origin on Plane-Paraboloid Intersection?

    Homework Statement Find the points nearest and furthest from the origin on the intersection of a plane with a paraboloid. Plane: x+y+2z=30 Paraboloid: z=x^{2}+y^{2} Homework Equations The Attempt at a Solution Obviously the first step is to find the equation of the...
  49. H

    Projectile motion - horizontal seperation of two points

    Homework Statement A projectile is fired with velocity v0 and passes through two points, both a distance h above the horizontal. The angle of the barrel of the gun is adjusted for the maximum range, find the horizontal separation of the two points. Homework Equations Max range for projectile...
  50. H

    Quartic with two stationary points of inflection

    Hey everyone! Recently got a question in maths which asks: "Use integral calculus to find the equation of the quartic that has stationary points of inflection at (1, 23) and (3, 15) and a y-intercept of 24" This means that the second derivative has the form (as inflection points are...
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