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This is the Exam of Mathematics which includes Four Roots, Quartic, Factorize the Quartic, Eulerian Representation, Lagrangian Position, Euler Lagrange Equations, Extrema, Functional etc. Key important points are: Differential Operator, Solution, Homogenous Equation, Wronskian, Construct, Second Solution, Initial Value Problem, Appropriate, Homogenous, Regular Singular Point
Typology: Exams
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Ly ≡ y′′^ − 2 y′^ +
1 − (^) x^22
y
in 1 < x < ∞. (a) Show that y(x) = x^2 ex^ is a solution to the homogenous equation Ly = 0. (b) Find a Wronskian for the equation Ly = 0 and hence construct a second solution to the homogenous equation. (c) Using a Green’s Function as appropriate for an initial value problem, solve Ly = xex with y(1) = y′(1) = 0.
xy′′^ + (1 − x)y′^ + ky = 0. (a) Show that it has a regular singular point at x = 0. (b) Find one power series solution to the ODE about the point x = 0, which is finite at x = 0. (c) What is the radius of convergence of the series solution? (d) Determine the values of the parameter k, = ν say, for which the series terminates as a polynomial; call such solutions Lν (x). (e) Rewrite the ODE in Sturm-Liouville form and hence deduce an orthogonality relationship for the different polynomial solutions Lν and Lμ(x), ν 6 = μ.
ex^ = (^21) π^ (e^2 π^ − 1 )^
n=−∞
einx 1 − in. By considering a particular value of x, deduce that
π coth π = π (e
2 π (^) + 1) e^2 π^ − 1 = 1 + 2
n=
1 + n^2. Similarly, show that a second choice for x leads to the result
π cosech π = 1 + 2
n=
(−1)n 1 + n^2.
f̂ (k) =
−∞^ f^ (x)^ e
−ikx (^) dx.
State the inverse transform which defines f (x) in terms of f̂ (k). The function f (x) is defined as
f (x) =
{ (^) e−x (^) for x > 0 , −ex^ for x < 0. (a) Find f̂ (k). (b) Use the convolution theorem to find the function g(x) which satisfies ∫ (^) ∞ −∞
f (y)g(x − y)dy = xg(x)
and takes the value g(0) = 1/ 2.