ODE 602S
Ordinary Differential Equations
November 2023
1. Solve the following initial value problems:
(a) y'(x) + 1y(x) = 6x - 5, y(l) = 1, for x > 0
(5)
(b) y'(x) + y(x) tanx = e2x cosx, y(0) = 2
(5)
(c) Cobalt-60, a radioactive element employed in medical radiology, possesses a half-life
of 5.3 years. Let's consider an initial cobalt-60 sample weighing 100 grams.
i. Caculate the decay constant and derive an equation representing the quantity
of the sample that will remian t years from now.
(5)
ii. What is the time required for 85% of the sample to undergo decay?
(5)
2. (a) Find the values of o: such that y(x) = e0 x is a solution of
y"(x) - y'(x) - 6y(x) = 0.
Determine if the solutions are linearly independent or not. Hence or otherwise,
write the general solution.
(6)
(b) Given that
ay"(x) + by'(x) + cy(x) = 0
1. Write down the atndliary equation.
(2)
11. If the roots of the auxiliary equation are complex and denoted by m 1 = o: + (3i
and m2 = a - (3i, show that the general solution is
(6)
(c) Find the particular solution of the following differential equations, using undeter-
mined coefficients
y"(x) - 6y'(x) + 8y(x) = 3cosx
(6)
3. (a) Find the general solution of
0.5yiv(x) + y"(x) + 0.5y = 0
(6)
(b) Find the general solution of
2y"'(x) + 6y"(x) - Sy= 0
(c) Find the general solution of
l8x 2 y"(x) + 30xy'(x) + lOy(x) = 0, x > 0
(6)
2
(8)