General solution Definition and 303 Threads

  1. M

    General Solution to a Singular System (or no solution)

    When I realize that I am going to have a singular matrix (after exhausting row swap options and maybe even some elimination steps) what about the matrix tells me whether or not I can have a general solution?
  2. T

    General solution of trig functions

    Homework Statement Find the general solution of: a) sin x = 1/\sqrt{2} b) cos x = 0.5 The Attempt at a Solution a) x = asin(1/\sqrt{2}) x = (π/4) + 2nπ b) x = acos(0.5) x = π/3 + 2nπ Basically, my strategy was to solve for the basic angle, and then add multiples of the...
  3. N

    General Solution to Linear, Homogenius, Second-Order Differential Equation

    I need to solve d/dx(e^(-(x^2))*(du/dx))=u+x*(du/dx) I get e^(-(x^2))*u''-2xe^(-(x^2))*u'=u+x*u' u''-2x*u'=e^(x^2)*u+xe^(x^2)*u' u''+(2x-xe^(x^2))*u'-e^(x^2)*u=0 but I have no idea how to approach the problem from here. Can somebody please help?
  4. V

    Find the general solution of a coupled differential equation:

    Homework Statement I want to find the general solution of these two equations, \ddot{y}=\omega\dot{z} \ddot{z}=\omega\left(\frac{\mathbf{E}}{\mathbf{B}} - \dot{y}\right) Homework Equations These two equations are the result of quantitatively solving to find the trajectory of a charged...
  5. S

    Solving Cauchy Problem: General Solution of xy3zx+x2z2zy=y3z

    Homework Statement getting gen sol of xy3zx+x2z2zy=y3z solve cauchy problem x=y=t, z=1/t The Attempt at a Solution i got gen sol F(C1,C2)=0 as C1=x/z, C2=y4-x2z2 i inserted t for x and y and 1/t for z and ended up with C1-2=1/(C22) I'm unsure what to do from...
  6. B

    General solution of third order DE

    Homework Statement y'''-3y'+2y=0 initial conditions y(0)=0, y'(0)=1,y''(0)=1 Homework Equations Assume y=e^{rt} The Attempt at a Solution By the substitution I'm left with r^3-3r+2=0 which gives me the roots of -2 and 1. my question is a lot of times with this type...
  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. I

    General Solution for ODE: y'' + 6y' + 9y = x*exp(-3x)3x

    Im having trouble with this question. can anyone explain please? Homework Statement y'' + 6y' + 9y = x*exp(-3x)3x Homework Equations Find the general solution.
  9. B

    Solve DE y' = \frac{y+y^2}{x+x^2} - Separation of Variables

    Homework Statement y' = \frac{y+y^2}{x+x^2} Homework Equations separation of variables The Attempt at a Solution I start with y' = \frac{y+y^2}{x+x^2} which is \frac{dy}{dx} = \frac{y+y^2}{x+x^2} next step is dy = \frac{y+y^2}{x+x^2}dx than I divide both sides by...
  10. X

    Finding the general solution to the DE

    Homework Statement (x^2)yy' = e^x Homework Equations general solution to the DE The Attempt at a Solution first i changed y' to dy/dx (x^2)y(dy/dx) = e^x then divided both members by x^2 and multiplied both members by dx ydy = (e^x)dx/(x^2) or ydy = (x^-2)(e^x)dx...
  11. estro

    General solution of linear system

    I have this question, but don't know how to even start. Suppose (M) is a linear system of 2 equations and 3 unknowns, where (2,-3,1) its solution. Suppose (O) is a matching homogeneous linear system, where (-1,1,1) and (1,0,1) its solutions. How can I find the general solution of (M)? I'm...
  12. Z

    What is the general solution for the given differential equation?

    Homework Statement y''+4y'+4y= t+exp(-2t) find the general solution for the differential equation Homework Equations The Attempt at a Solution general solution is sum of complementary function and particular integral frist finding complementary function y''+4y'+4y=0...
  13. jinksys

    Find a general solution [Diff Eq]

    Homework Statement Find a general solution for y''' - 6y'' + 9y' = 0 Homework Equations The Attempt at a Solution I know that the general solution for a homogeneous DEQ is Y(x) = c1y1(x) + c2y2(x) ... cnyn(x) however, I am not given y1, y2 , or y3 so I am to assume that the...
  14. H

    General Solution to time independent schrodinger equation

    Homework Statement This is really a maths problem I'm having. I need to get the general solution for the infinite square well in the form: u = A cos(kx) + B sin(kx) I found the general solution to be: u = A exp(ikx) + B exp(-ikx) Using Euler's formula: exp(ikx) =...
  15. I

    What are the methods for solving y''' + y' = tan(t) 0<t<pi?

    y''' + y' = tan(t) 0<t<pi I got yh = c1 + c2cos(t) + c3sin(t) I'm trying to solve by Undetermined Coefficient method and Variation of Parameters method, but it didn't work
  16. S

    What is the general solution for y'' + 4y' + 4y = 5xe^(-2x)?

    Homework Statement Find the general solution y'' + 4y' +4y = 5xe^(-2x) The Attempt at a Solution I got (5/2)x^3*e^(-2x) as a particular solution. But I checked online at wolfram alpha and it says the particular solution is (5/6)x^3*e^(-2x). Using method of undetermined coefficients.
  17. N

    Finding the General Solution for xX' = aX

    Question: find the general solution of xX' = aX i know it's kinda simple ode.. but, i just don't know y i can't get the correct answer.. solution.. xX' = aX x dX/dx = aX d/dx X = aX/x X = ∫aX/x dx X = aX ln |x| + C the general solution is Ax^a problem : i can't get the...
  18. D

    Please check my work (find general solution of DE)

    Homework Statement "find the general solution of the equation: y'' + 3y' + 2y = 0 characteristic is: r^2 + 3r + 2 = 0 solve quadratic: (r+2)(r+1) r = -2 r= -1 therefore GS of equation is: y = c_1e^-2x + c_2e^-x thanks for any help Homework Equations The Attempt at a Solution
  19. N

    General solution of ode using fourier transform

    ok well I'm pretty much home and dry in this problem the aim of this problem is to get the general solution for the ode below.. 2u'' - xu' + u = 0 = g(x) i started to solve it by rearranging the equation.. 2u'' + u = xu' apply Fourier transform.. 2F(u'') + u^ = g^ (-2k^2)u^ + u^...
  20. A

    Is this general solution for ODE correct?

    [b] Find the general solution of the following ODE: dx/dt = 3x^(2) cos t [b] Make x the subject of the solution. [b] Heres my solution, is this correct? dx/dt = 3x^(2) cos t dx/3x^(2) = cos t dt Integrating both sides gives: ln (3x^(2)) = sin t + C 3x^(2) =...
  21. A

    Finding general solution for y(t): Very Difficult

    Find y(t) assuming that y(0) = 4000 Homework Equations This is what I know! v = 20√10 x ((1+Ae^(t/√10))÷(1-Ae^(t/√10))) and A = -1 when finding particular solution to satisfy initial condition v(0). Terminal velocity = 63.246 m.s^-2 The Attempt at a Solution...
  22. A

    Finding general solution for object falling in air

    [b]1. Using separation of variables show that: v' = (cd/M)(v^2) - g has a general solution of: v = 20SQRT10 x ((1+Ae^(t/SQRT10)/(1-Ae^(t/SQRT10)) Homework Equations The Attempt at a Solution Have attempted numerous times with little success help appreciated!
  23. A

    Solving ODE to find general solution

    If we assume air resistance is negligible, the only force acting on a body is -Mg where g is the acceleration due to gravity ( negative because acting downwards). F = Ma becomes : -Mg = M y'' which implies y[B]''=-g Question asks find the general solution for y. Homework Equations...
  24. M

    Finding general solution of (d^2 x)/dt^2 + k/(L-x) = 0

    Homework Statement does this ode have a general solution? \frac{d^2 x}{d t^2} + \frac{k}{L -x} = 0 Homework Equations The Attempt at a Solution
  25. I

    Looking for General solution for a difference equation

    At+1=(At+r)/(At+r+1) A1=constant I know I can set At+1=At=A and solve for a special solution. What would be a general solution? I am not taking a course in Difference Equation, and this is not my homework but I encounter a similar question and I reduce it to this form. Thanks
  26. K

    General solution to a second order homogeneous differential equation

    Homework Statement Find if it is true that the general solution to : y'' - y' = 0, where y(x), can be written as : y(x) = c1 cosh(x) + c2 sinh(x), where c1 and c2 are real arbitrary constants. Homework Equations differential equation solving The Attempt at a Solution I just...
  27. ExtravagantDreams

    Simple integral, example or general solution correct?

    This should be very simple, but I can find a simple example that violates my general conclusion. I clearly must be doing something wrong with my integration by parts. Any suggestions would be great. Define a distribution such that the density; \eta(\vec{x})=\int d\vec{k} f(\vec{x},\vec{k})...
  28. P

    Linear Algebra General Solution

    Homework Statement Find the general solution to the system: ax+ by= 1 cx+ dy= 2 Consider the case when ad- bc \neq 0 The attempt at a solution Like in my other post, I multiplied the first equation by "c" and the second equation by "a", and then I subtracted the two equations. I...
  29. P

    General Solution Linear algebra

    Homework Statement Find the general solution to the system: ax+ by= 0 cx+ dy= 0 Consider the case when ad- bc\neq 0 The attempt at a solution I multiplied the first equation by "c" and the second equation by "a", and then I subtracted the two equations. I got the following...
  30. B

    General solution to a simple ODE

    Whenever I am stuck I usually manage by sitting down and working on the problem and eventuall finding the solution, this one is bothering me too much and I don't have any class until friday so no hope of finding out before then unless I ask here. Q: Find a general solution to the diff.eq...
  31. C

    Finding the general solution to a differential equation

    Homework Statement \frac{d^{2}y}{dt} +4\frac{dy}{dt}+20y=e^{-2t}(sin4t+cos4t) Homework Equations The Attempt at a Solution The solution to the homogeneous equation: \frac{d^{2}y}{dt} +4\frac{dy}{dt}+20y=0 is y= k1e^{-2t}cos4t +k2e^{-2t}sin4t Then I guessed ae^{-2+4i} as a...
  32. D

    Finding General Solution / Fundamental matrix

    Morning everyone, Studying for a test and having a problem on a practice question he gave us to study with. Here's the question along with the answer: Y' = AY + [e^t e^-t 0] with A = [-1 0 4 -0 -1 2 0 0 1] the...
  33. J

    What is the General Solution for a Differential Equation with Complex Roots?

    Homework Statement (D^2 + 2D + 10)^2 * (D^2 - 2D -3)y = 0. Homework Equations D = d/dx The Attempt at a Solution Solving for the roots gives: -1 + 3i, -1 - 3i <== both of multiplicity 2 and 3, -1. So the general solution should be: y = Ae^(3x) + Be^(-x) +...
  34. D

    General solution of initial value problem -dont understand problem is asking me?

    General solution of initial value problem --dont understand problem is asking me?? Homework Statement Find a value for y-sub-0 for which the solution of the initial value problem: y' - y = 1+ 3sin t y(0) - y-sub-0 remains finite as t approaches infinity. (i called it "y-sub-0" , just...
  35. S

    General Solution to ODE Quiz Problem: Find n and C for y=Cx^n as a Solution

    Homework Statement This was a quiz problem Give the value of n and C for which y=Cx^n is a solution of the equation xdy/dx - 6y = 0Homework Equations ans n= 6 C= 0 (some triangle symbol) an n .. ineligible mark The Attempt at a Solution n = 6 C = All real numbers my tutor explained it...
  36. C

    General solution formula of a differential equation

    Hello, The general solution of a differential equation for y'+P(x)y=G(x) is y(x)=e^{-\int P(x)dx}[C+\int e^{\int P(x)dx}G(x)dx] for y'+xy=x y(x)=e^{-\int xdx}[C+\int e^{\int xdx}xdx] i have y=Ce^{-\frac{x^2}{2}}+1 By the other solution \frac{dy}{dx}+xy=x \rightarrow...
  37. D

    Finding the General Solution for a Second Order Differential Equation

    Hi, I came across the following differential equation: \sqrt{1+(y')^2}=\frac{d}{dx}\left(y\frac{y'}{\sqrt{1+(y')^2}}\right) I found possible solutions: y\left(x\right)=cosh(x+C_{1}). However, this is a second order ODE so there exist a more general solution, with 2 freedom degrees...
  38. D

    General solution to 2nd order DE

    Hi, I am just looking for clarification whether or not I am doing these problems correctly, here's an example: Homework Statement Find the general solution to x'' -2x' + 5x = 0 Homework Equations Charasteristic polynomial. Quadratic equation. General solution form for complex...
  39. M

    General solution of differential equation system

    Homework Statement Find the general solution of the system of differential equations x'=10x - 12y y'=25x - 30y (where primes indicate derivatives with respect to t) by using the initial conditions x(0)=A y(0)=B Homework Equations The Attempt at a Solution x''=10x' - 12y'...
  40. W

    General solution of a linear system (differential equations)

    Homework Statement x''+13y'-4x=6sint , y''-2x'-9y=0 The Attempt at a Solution I am not really sure how to solve this completely, but I have done this so far: (D^2-4)x + 13Dy - 6sint = 0 , (D^2-9)y - 2Dx = 0 then I hit a brick wall. Any help would be appreciated, thanks.
  41. K

    Do These Functions Form a Fundamental Set for the Differential Equation?

    Homework Statement Verify that the given functions form a fundamental set of solutions of the differential equation on the indicated interval. Form the solution. 4y^{''} - 4y^{'} + y = 0 e^{x/2}, xe^{x/2} Homework Equations...
  42. Y

    How to Show the General Solution to the Poisson Equation?

    Homework Statement Given that \nabla2 1/r = -4\pi\delta3(r) show that the solution to the Poisson equation \nabla2\Phi = -(\rho(r)/\epsilon) can be written: \Phi(r) = (1/4\pi\epsilon) \int d3r' (\rho(r') / |r - r'|) Homework Equations The Attempt at a Solution I know...
  43. I

    Find general solution to Bessel's equation with substitution

    Homework Statement 81x^{2}y'' + 27xy' + (9x^{\frac{2}{3}}+8)y = 0 Hint: y = x1/3u x1/3 = z 2. The attempt at a solution Change of variables gives: \frac{d^{2}y}{dx^{2}} = x^{\frac{1}{3}}\frac{d^{2}u}{dx^{2}}+\frac{2}{3}x^{-\frac{2}{3}}\frac{du}{dx} - \frac{2}{9}x^{-\frac{5}{3}}u...
  44. K

    General solution to PDE: f(x-y) = g(y-x) for arbitrary functions f and g?

    Homework Statement Quote: " PDE: ∂u/∂x + ∂u/∂y = 0 The general solution is u(x,y) = f(x-y) where f is an arbitrary function. Alternatively, we can also say that the general solution is u(x,y) = g(y-x) where g is an arbitrary function. The two answers are equivalent since u(x,y) = g(y-x) =...
  45. C

    Solving DE: dr/d(theta) + r*sec(theta) = cos(theta)

    dr/d(theta) + r*sec(theta) = cos(theta) apparently the solution is (sec(theta) + tan(theta))*r = theta - cos(theta) + c but i have no idea how to get there. i am using a technique from the book, but it yeilds an answer with lots of e's and an integral i can't solve. this is my work...
  46. G

    Trig General Solution: Solve for x using sin2x = 0.5

    Homework Statement Solve for x using general solution sin2x = 0.5 Homework Equations sin2x= 2sinxcosx The Attempt at a Solution arcsin0.5 = 2x 2x = 30 degrees + k360 x = 15 degrees + k180. Or 2x = (180-30) + k360 2x = 150 + k360 x = 75 + k180
  47. K

    General solution to PDEs-arbitrary constants

    Homework Statement Claim: For the partial differential equation ∂u/∂x + ∂u/∂y = 0, the general solution is u(x,y) = f(x-y) Homework Equations N/A The Attempt at a Solution I remember that the number of arbitrary constants in the general solution should be the same as the order of the...
  48. A

    Differential Equations: Finding the General Solution

    Hello, this is the first time I post here, I'm really stumped and tried everything, even my TI-89 calculator won't give me something nice XD Homework Statement Find the general solution of dy/dt= 1/(ty+t+y+1) Homework Equations No relevant equations. The Attempt at a...
  49. L

    Wave equation, general solution, cylindrical symmetry

    I was interrested in the general solutions to the wave equation depending on only one spatial coordinate. For one linear coordinate, the general solution is: a f(x-ct) + b g(x+ct) For one radial spherical coordinate, the general solution is: a f(r-ct)/r + b g(r+ct)/r I thought that...
  50. R

    Find the general solution of Bernoulli Eq

    Problem:y' + y(1/x) = 3 x^2 y^2 Solution:p(x)= 1/x q(x) = 3x^2 <--- These are countinuous functions on the interval (0,+inf) y^-2[y' + y(1/x) = 3 x^2 y^2] A => y'y^-2 + y^-1(1/x) = 3x^2 v = y^(-n+1) = y^-1 v' = -y^-2 y' Plugin to problem A v' + v/x = 3x^2 B p(x) = 1/x...
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