ODE 602S
Ordinary Differential Equations
November 2022
l. Solve the following initial value problems:
(a) x 2y'(x) + 5x3y(x) = e-x, y(-1) = 0, for x < 0
(5)
(b) sinxy'(x) + cosxy(x) = 2ex, y(l) = a, 0 < x < 1r
(5)
(c) If a constant number k of fish are harvested from a fishery per unit time, then a
logistic model for the population P(t) of the fishery at time t is given by
ddP,t(t) = -P(t)(P(t) - 5) - 4, P(0) = Po
1. Solve the IVP.
(5)
11. Determine the time when the fishery population becomes half of the initial
population
(5)
2. (a) If y1 and y2 are two solutions of second order homogeneous differential equation of
the form
y"(x) + p(x)y'(x) + q(x)y(x) = f(x)
where p(x) and q(x) are continuous on an open interval I, derive the formula for
u(x) and v(x) by using variation of parameters.
(6)
(b) If
find y2 (x)
(7)
(c) Solve
8x2y"(x) + 16xy'(x) + 2y(x) = 0
(7)
3. (a) Find the general solution of
(6)
(b) Find the general solution of
y"'(x) - 6y"(x) + lly'(x) - 6y = e- 2x + e- 3x
(7)
(c) Solve the following differential equations simultaneously
dx
dt
+ 5x(t)
-
2y(t)
=
t,
dy
dt
+ 2x(t)
+ y(t)
=
0
(7)
4. (a) Calculate
.C{9t4 + 6t~}
(6)