Mathematics Homework Solutions

Sobolev Spaces

See attached question. I think the answer is alpha < n/p - m, but I would like a detailed explanation.

Partial Differential Equations and the Lagrange Method

1. solve X*U_x + Y*U_y =0 answer is suppose to be U(X,Y)=f(Y/X) 2. solve U_x + U_y =1 answer unknown

Sobolev Spaces

Please see the attached file for the fully formatted problems.

Interpolation Inequality and Sobolev Spaces

Please see the attached file for the complete solution. Thanks for using BrainMass.

Wave Equations and Energy Density

For a solution of the wave equation with p=T=C=1 the energy density is defined as e=1/2 (U_t ^2 + U_x ^2) and the momentum density as p=U_t*U_x Show that de/dt=dp/dx and dp/dt=de/dx Show that both e(x,t) and p(x,t) also satisfy the wave equation http://tosio.math.toronto.edu/pdewiki/index.php/2006APM346Midterm1 It's ...continues

Trigonometric Systems and Inner Products; Two-Dimensional Laplace Equations

Please see the attached file for the fully formatted problems.

Diffusion Equation

Show that S(x,y,t)=S(x,t)S(y,t) satisfies the diffusion equation. S_t = k(S_xx + S_yy)

Wave Equations and Periodic Differentiable Functions

3. Solve the wave equation, ∂2u/∂t2 = c2(∂2u/∂x) -∞ < x < ∞ With initial conditions, u(x,0) = (1/x2+1)sin(x), and ∂u/∂t(x,0) = x/(x2+1) 4. Suppose that f is a 2п-periodic differentiable function with Fouier coefficients a0, an and bn. Consider the Fourier coeffici ...continues

A solution of the wave equation using D'Alembert's solution

Solve the wave equation subject to the initial conditions u(x,0)=sin(x)/(x^2+1), du/dt(x,0)=x/(x^2+1)

The Fourier coefficients of a derivative

Let f be a 2 pi periodic, differentiable function with Fourier coefficients a_n and b_n. Let (a_n)*, (b_n)* be the Fourier coefficients of f'. a) Show that (a_0)*=0 b) Use integration by parts to find a formula for the Fourier coefficients of f' in terms of the Fourier coefficients of f. (The attachment contains the ...continues

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