Roots Definition and 962 Threads

  1. E

    What is the Number of Complex Roots for the Given Equation with Varying d?

    How many complex roots admit the following equation: (2 z^2 + 1)^2 ((z + d)/(z - i))^1/2 - (2 z^2 - d)^2 ((z + i)/(z - d))^1/2 == 0 for 0 < d < 1, where i = (-1)^1/2. Can I found how their number varies with d by using the argument principle? Thanks in advance for helpfull suggestions
  2. D

    MATLAB-finding roots and summations

    Homework Statement (all this is included in the attachment, btw) p(z)=z^4+4.25*z^2+1 1. use MATLAB to find the four roots Ck of p(z)= 0 2. For all complex constants ck (different than Ck) define the complex valued function Z(t)= 4\Sigmak=1 ck*exp(Ck*t)...
  3. W

    Are the doppler effects of sound wave and light wave of different roots?

    is the light doppler effect a purely relativistic effect? or it is present even in the classical limit?
  4. H

    How to solve recurrence relation with one real root and two complex roots ?

    How to solve recurrence relation with one real root and two complex roots ? The Example is ; Solve the recurrence relation a n-1 + a n-3 = 0 where n ≥ 3 and a 1 = 1 a 2 = 1 a 3 = 2 a n = nth order a n-1 = (n-1)th order. a n-3 = (n-3)th order. I've started the solving ; a n = r^n so...
  5. L

    Roots of Lie Algebra (Jones book)

    Hi, If anyone has a copy of this book, I'm just struggling to understand a point in the chapter about Lie Groups. In particular the section on qunatization of the roots, on p177-178, he generates the diagrams in fig 9.2 from those of 9.1. I thought I understand this, but I don't understand...
  6. Telemachus

    Finding the roots through Newtons method

    Homework Statement In each of the following items approximate the zeros of f using Newton's method. Continue iterating until making two successive approximations differ at most in 0.001. The Newton iteration: x_{n+1}=x_n-\displaystyle\frac{f(x_n)}{f'(x_n)} Well, I have a doubt about this. I'm...
  7. B

    Check DE general solution with complex roots

    Homework Statement Solve y''+4y'+5y=0 find solutions for y(0)=1 and y'(0)=0 Homework Equations Quadratic equation The Attempt at a Solution Hows this look ? assume solution is in the form of y=ce^{rx} substitute y=ce^{rx} into the equation...
  8. N

    How do roots avoid getting clogged

    Plant roots absorb water and nutrients for the life of the plant. What keeps the exterior surface of the root cells from becoming clogged...say with dirt or other matter. Any filter eventually becomes clogged and needs to be cleaned, how about plant roots? One possibility is that surface...
  9. D

    Help Getting the roots of a polynomial

    Homework Statement I am trying to get the roots of: (x-a)^3 - (x-a)b^2 - 2b^3 -2b^2(x-a) which I know they are x = a-b and x = a+2 b the problem is, how can I reach that solution ? The Attempt at a Solution At first I thought of separating the independent term (the one...
  10. P

    Find All Values of k for Equal Roots in x^2-kx+4=0

    Homework Statement Use the disciminant to determine all values of k that would result in the equation x^2 - kx + 4 = 0 having equal roots. Homework Equations x = -b +/- (square root) b^2 - 4ac and divide by 2a or b^2 - 4ac The Attempt at a Solution a = 1 b = - 1 c = 4 I'm...
  11. S

    Limit of logarithm of square roots function

    Homework Statement I need to prove that the following limit holds when \sqrt{s}>>m \log\left(\frac{\sqrt{s}+\sqrt{s-4m^2}}{\sqrt{s}-\sqrt{s-4m^2}}\right) \rightarrow \log\left(\frac{s}{m^2}\right) The Attempt at a Solution I've tried several manipulations using logarithms properties but had...
  12. R

    Graphical representation of complex roots to equations

    I've never properly studied complex numbers but I will soon (in September). Basically: We get taught from a young age that: the real root of f(x)=x²-4 is where the graph of y=f(x) cuts the x axis But is there a graphical representation of a complex root? What's so special about the...
  13. M

    Roots of Polynomials: Finding g(y) with y1, y2, y3

    Homework Statement Let x1, x2, x3 are the roots of the polynomial f(x)=x3+px+q, where f(x)\inQ[x], p\neq0. Find a polynomial g(y) of third degree with roots: y1=x1/(x2+x3-q) y2=x2/(x1+x3-q) y3=x3/(x1+x2-q) Homework Equations The Attempt at a Solution Any ideas? Thank you.
  14. P

    Determine the indicated roots of the complex number

    [2(cos(pi/3)+isin(pi/3))]1/2 I simplified it to 21/2(cos(pi/6)+isin(pi/6)), but I have no idea what else to go to. Any tips would be very helpful, thx in advance
  15. J

    Can Induction Prove a Polynomial of Degree n Has At Most n Roots?

    I'm trying to prove that a polynomial function of degree n has at most n roots. I was thinking that I could accomplish this by induction on the degree of the polynomial but I wanted to make sure that this would work first. If someone could let me know if this approach will work, I would...
  16. R

    Proving the Roots of Higher Derivatives of a Polynomial Function

    Let f (x) = (x^2 − 1)^n . Prove (by induction on r) that for r = 0, 1, 2, · · · , n, f^ (r) (x)(the r-th derivative of f(x)) is a polynomial whose value is 0 at no fewer than r distinct points of (−1, 1). I'm thinking about expanding f(x) as the sum of the (n+1) terms, then it's easier to...
  17. S

    What is the Problem with Calculating Roots of a Quartic Equation?

    Hey guys, I've been working on this computer application, and ended up needing to compute the roots of a quartic equation. So I implemented Ferrari's method and the results for the most part are working, however I've come across a few exceptions where I'm getting incorrect results. For...
  18. T

    Integral problems with roots of polynomials

    Homework Statement How do i solve this integral ? \int \big( \sqrt{x^{3}+1} + \sqrt[3] {x^{2}+2x} \big) \ dx Homework Equations The Attempt at a Solution what is the appropriate substitution to make here
  19. J

    MATLAB Matlab Polynomial Equation Roots Approximations

    Is there a function in Matlab which gives a list of numerical approximations to the roots of a polynomial equation (eg. like NSolve in Mathematica?) Thanks!
  20. sylas

    What Are My Experiences Discovering My Korean Heritage in Seoul?

    I'm currently in Seoul, Korea. My last blog here warned I might be gone for a bit, but I have internet at my current accommodation, so here's a hi! You can find out more about why I might be in Korea from my very first blog entry: https://www.physicsforums.com/blog.php?b=1316 . I've come home...
  21. T

    Find Range of k for Two Positive Roots of Equation

    Homework Statement Find the range of the number k so that the equation 100^x-10^(x+1)+k=0 has two distinct positive roots Homework Equations The Attempt at a Solution I know if it says for two distinct roots only , k<25 but now its two distinct POSITIVE roots , so how ?
  22. I

    Arguments of Roots of Complex Numbers

    Homework Statement i) Solve the equation z^3 = \mathbf{i}. (ii) Hence find the possible values for the argument of a complex number w which is such that w^3 = \mathbf{i}(w*)^3. I'm stuck on part ii. Homework Equations The Attempt at a Solution The answer to the equation in...
  23. M

    Quadratic equation with roots of α and β

    Homework Statement The quadratric equation x^2 - 5x + 7 = 0 has the roots α and β. Find the quadratic equation with roots α^3 and β^3. Homework Equations N/a The Attempt at a Solution u = α^3 α = u^(1/3) u^(2/3) - 5(1/3) + 7 = 0 u^(1/3)[u - 5] = -7 --- minus 7 off each...
  24. Q

    Unclear situation involving roots.

    Let's say we have: A=B3 r=6B2 and we want to rewrite A in terms of r. My way to do it is: B2=r/6 => B=+-\sqrt{(r/6)} => B3=+-(r/6)\sqrt{(r/6)} => A=+-(r/6)\sqrt{(r/6)} In a book I found...
  25. B

    What is the Limit of the Product of Roots as n Approaches Infinity?

    Lt (1 – 1/√2)* (1 – 1/√3)…… (1 – 1/√n+1) n->∞ There must some simple calculation to find this, but I cannot get this, limit exists since each tern is less than 1, and limit is more than 0. so limit exists between (1 0).
  26. S

    What Are the Roots of z^n = -1 in Complex Numbers?

    Homework Statement What are the roots of z^n = -1 Homework Equations The Attempt at a Solution are they e^{\frac{2\pi k i}{n}-\frac{i \pi}{n}} ?
  27. J

    Why nth Degree Equations Have n Roots?

    Why is it said that an equation of nth degree must possesses n roots ? if x^1 = y, x has only 1 value x^2 = y, x has 2 values (the 2 values may be equal) x^3 = y, x has 3 values going on like this, we have, x^0 = 1 , implies x has no solutions. but x has infinite number of solutions.
  28. P

    What is the Solution to a Function and Roots Problem?

    Homework Statement F(X)=√x F((F(2)-2)^2)+f(2) Homework Equations The Attempt at a Solution I get to √(-4√2 +8) ... that minus sign is annoying me =] any help?
  29. S

    Question on ODE's with roots of multiplicity.

    I was wondering how the general formula for the solutions of an nth order linear homogeneous ODE that had a characteristic equation which could be factored to (x-a)^n was derived(IE a set of solutions consisting e^(mx), x*e^(mx), ...x^(n-1)e^(mx)))? For example the ODE, y^(3)- 3y'' + 3y'...
  30. J

    Another repeated roots problem

    Homework Statement Find the solution of the initial value problem. x'=[3 9; -1 -3]x, x(0)=(2 4)T Homework Equations A good guess should be x=tert$ + ert# The Attempt at a Solution But ... the only root is r=0, which gives me a solution x(1)(t)= C1(-3 1)T. Using the...
  31. C

    MATLAB How can you solve non-polynomial equations using MATLAB?

    I have a function : f (n)=40*n^1.5-875*n+35000; How can i solve this equation with MATLAB. I know how to solve polynomial equation but this is different i think.
  32. Q

    Second order DE involving repeat roots

    ok, for 2nd order differential equations, if we have repeat roots, like for example y" +4y = cos2x , we would have repeat roots +2i,-2i. so how do we try for the particular solution? i tried Acos2x + Bsin2x, it all canceled out. i tried (Ax+B)cos2x + (Cx+D)sin2x it all canceled out too then...
  33. H

    Proving the Three Cube Roots of 1 with w

    Homework Statement Let w be a primitive cube root of 1. show that 1, w,w^2 are the three cube roots of 1. Homework Equations The Attempt at a Solution I'm not quite sure how to even start this. any help will be greatly appreciated.
  34. r-soy

    Find six distanct sixth roots of -1 + i root 3 I want check my answer

    Find six distanct sixth roots of -1 + i root 3 I want check my answer ==== > x = -1 y = root 3 r = 2 tan Q = 2pi/3 -1 + i roo3 = 2 { cos ( 2 pi / 3 ) + i sin 2 pi / 3 ) = 2 e ^2 pi i / 3 } now six root -1 + i roo3 = 2^1/6 e ( 2 pi/3...
  35. P

    Mathematica Finding the first roots of a function with Mathematica

    Hello everyone, I have just created my account here and so this is my first post and I would like to appologise if my question may have been posted by someone else. I am new to mathematica but I am very found of the program. So much so that I am trying to use it for one of my research...
  36. C

    Valid Estimation of Square Roots?

    I've been playing around with a forumlaic representation of a known square roots estimation method and I came up with this: This estimation has several interesting properties to it which I've been looking into. My main concern is the fact that I'm using SQRT(x) in the equation which...
  37. B

    Fixed point iteration to find the roots of 0=x-tan(x)

    Homework Statement The question wants me to first estimate the roots by drawing the graph and then by using a 'suitable' fixed point method to determine the first 4 positive roots. Homework Equations 0=x-tan (x) I rearranged to get x=arctan (x) so that the series x_n will converge...
  38. M

    What do I do with the +- in y'= +-(2y^3)^1/2?

    So there's this ODE: yy''-(y')2 = y3 After doing some work it gets to this point: (y')2=2y3 Taking the root: y' = +-(2y3)1/2 My question is, what do I do with the +-? Do I solve 2 different integrals? Assume that this is positive? Does it matter if it has starting conditions (y(x)=a...
  39. P

    Finding a Complex Number w for Fifth Roots of 1 - Need Help?

    Show that a complex number, w exists such that the fifth roots may be expressed as 1, w, w^2, w^3 and w^4I am having trouble understanding what the question is asking of me. Could anyone please help? Thanks.
  40. T

    Simple roots of a Lie Group from the full root system

    Hello all, I'm attempting to find in literature a method of determining from a Lie algebra's full root system in an arbitrary basis which roots are simple. It seems there are many books, articles, etc on getting all the roots from the simple roots but none that go the other way. My task is...
  41. D

    Can the Roots of x^4 + 7x^2 + 6 = 0 be Imaginary?

    x^4 + 7x^2 + 6 =0 I know the answers are imaginary but I don't remember how to solve this equation.
  42. D

    Linear Combinations of Trig Functions - Finding Roots

    Hi there I was wondering if there is a simple way to solve for the roots of a complicated summation of trig functions that can't be combined with any simple identities. I have an equation of the form: 0 = sin(8x-arctan(4/3))+3.2sin(16x+pi/2) where the two sines have different amplitudes...
  43. M

    Finding a,b from roots of equition

    Homework Statement If x = -1; 1 are the two roots of the equation x^2 +ax+b = 0; then find the values of a and b. The Attempt at a Solution x^2+ax+b=0 (x-1) (x+1)= 0 ,,,,,, by expanding x^2-1=0 ,,,,, so a=0 , b=-1 is it right or the question is asking for something eles,,,, ?
  44. M

    3 cube roots, 4 fourth roots, and N nth-roots of -1

    My "Computational World" class is supposedly an intro to computer science without programming, but the questions are all over the place. I'm completely stuck on this question: Show expressions for: (a). 3 cube roots of -1 (b). 4 fourth roots of -1 (c). In the general case, N nth-roots of...
  45. Mentallic

    Explore Why e^x Has Zero Roots Despite Being an Infinite Degree Polynomial

    The function y=e^x can be expanded using the power series, thus y=e^x=1+x+\frac{x^2}{2}+\frac{x^3}{3!}+... This is a polynomial of infinite degree, and the theorem that says a polynomial must have at least one root in the complex field, and thus this extends to a polynomial of nth degree having...
  46. N

    Triangular numbers - Roots with bases other than 1

    Not sure where this should go, but - How would you calculate the square root of a triangular number with a base other than 1? For example, 2, 6, 12, 20 (Base 2). Would rather have help to figure it out than the actual formula.
  47. O

    Solving for k and m in a Quartic Equation

    Homework Statement The equation x4-6x3-73x2+kx+m=0 has two positive roots, \alpha \beta, and two negative roots, \delta \gamma. It is given that \alpha\beta=\delta\gamma=4 (i) Find the values of k and m Homework Equations stated above The Attempt at a Solution m =...
  48. B

    Square roots of positive numbers

    Homework Statement If a and b are positive real numbers, and \lambda^{2} = ab, then \lambda = \pm \sqrt{ab}. Homework Equations None. The Attempt at a Solution This is more of a conceptual question that has always escaped me. I do not understand how the square root of two...
  49. M

    Is there an equation to find roots?

    Is there a mathematical equation to find square/cubic/etc. roots of a number? Any help would be greatly appreciated - this is purely for my own interest. Also, I;m doing the C2 module of AS Maths so I may not understand more complex terms used in an explanation (if any are needed) - apologies...
  50. I

    Cubic Equation Roots: Solving for α and β | p Value Calculation

    Homework Statement The equation x3 − 3x2 + px + 4 = 0, where p is a constant, has roots α −β , α and α + β , where β > 0. (a) Find the values of α and β . (b) Find the value of p. how do i start off? all i know is that sigma a= -b/a and ab= c/a and ab(gamma) = -d/a . Would this be one of...
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