Assignment title: Information
MXB106 Take Home Assignment 4
Question 1
Consider a spherical object whose steady state temperature distribution is described by the equation
12r
ddr
r2 d dru(r) = 0
on the domain 1 < r < 2. Solve for the temperature distribution with boundary
conditions
u(1) = 0.5 and u0(2) = 0.5
and plot the temperature distribution over the relevant domain.
Question 2
Consider the following non-homogeneous ODE
y00(t) − 8y0(t) + 16y(t) = kd(t)
where k is a constant and d(t) is the Dirac delta function. Solve this ODE using
Laplace transforms with the boundary conditions y(0) = a and y0(0) = b.
Question 3
Consider the second order differential equation
y00(x) + p(x)y0(x) + q(x)y(x) = 0
Given that y(x) = y1(x) is a known solution to this ODE, find a second solution,
y2(x) in terms of y1(x), p(x), and q(x).
Question 4
Solve
y00(x) + 9y(x) = 0
where y(0) + y0(0) = 0 and y(p) − y0(p) = 10. Plot the solution on the domain
0 < x < p.
1Question 5
Solve the following differential equation
y00(x) + y0(x) = 1
1 + ex
via variation of parameters.
Question 6
Given that y1(x) and y2(x) satisfy the differential equation
f1(x)y00(x) + f2(x)y0(x) + f3(x)y(x) = 0
show that
y(x) = c1y1(x) + c2y2(x)
also satisfies this differential equation.
Question 7
Find the values of a such that the system
~ x0(t) = a 3 − −9 3~ x(t)
will have periodic solutions.
Question 8
Determine the asymptotic stability of the solution ~ x = (0, 0)T for the system
~ x0(t) = − c4 3 1~ x(t)
for c = 5, 7, and 10.
Question 9
Find the Laplace transform of
tn f 0(t)
where n ≥ 1.
2Question 10
The fundamental set solutions of a third order ODE whose characteristic polynomial has one real root and two complex roots is
y1(t) = el1t, y2(t) = eat cos(bt), and y3(t) = eat sin(bt)
where l1,2 = a ± bi. Prove that y1(t), y2(t), and y3(t) indeed form the fundamental
set of solutions, i.e. prove they are linearly independent.
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