Indian Institute of Technology Ropar
Department of Mathematics
MA201 : Differential Equation (UG Course)
1st semester of academic year 2018-19
Tutorial Sheet-4 Second Order ODE
1. Find particular solution of differential equation by method of undetermined coeffi-
cients:
(a) y 00 + 3y 0 = 2t4 + t2 e−3t + sin(3t)
(b) x2 y 00 − 2xy 0 + 2y = 6 ln(x)
2. If the number c is an m-fold root of polynomial equation P (r) = 0 then, P (r) =
Q(r)(r − c)m , where Q(c) 6= 0. Show that in this case the differential equation:
P (D)y = Aecx ,
possesses the solution
A
y(x) = xm ecx .
m!Q(c)
3. Find the solution by undetermined coefficients:
y 00 − y 0 − 2y = 4x2
that satisfies y(0) = 0 and y 0 (0) = 1.
4. Find particular solution of
y 00 − 3y 0 − 4y = 2e−t .
5. Determine the solution of
(
t, 0 ≤ t ≤ π,
y 00 + y =
πeπ−t , t > π,
satisfying the initial conditions y(0) = 0 and y 0 (0) = 1. Assume y and y 0 are
continuous at t = π.
6. Solve the ODE:
(
1, 0 ≤ t ≤ π/2,
y 00 + 2y 0 + 5y =
0, t > π/2,
with the initial conditions y(0) = 0 and y 0 (0) = 0.
7. Given y1 (t) = t−1 solution of
2t2 y 00 + 3ty 0 − y = 0, t > 0.
Find fundamental set of solutions.
8. Solve by method of variation of parameters:
(a) y 00 + 4y 0 + 4y = t−2 e−2t .
(b) y 00 + 4y = 8 tan(t), − π/2 < t < π/2.
9. Solve:
e2x
y 00 − 3y 0 + 2y = − .
ex + 1
10. The equation
1
x2 y 00 + xy 0 + (x2 − )y = 0, (a)
4
1
is a special case, corresponding to p = 2 of Bessel’s equation
x2 y 00 + xy 0 + (x2 − p2 )y = 0.
Verify that y1 (x) = x−1/2 is a solution of (a) for x > 0 and find general solution.
11. Find the general solution of the differential equation, given one solution of homoge-
neous equation:
xy 00 + (1 − 2x)y 0 + (x − 1)y = 0, y = ex .
12. Consider:
xy 00 − (1 + x)y 0 + y = x2 e2x .
Solve for general solution to this ODE.
13. Find the general solution of:
00 0 et
y − 2y + y = 2
+ 3et .
1+t
14. Solve:
y 00 + 4y = tan(2t) + e3t .
15. Solve the second-order non-homogeneous linear differential equation
√
x2 y 00 − 3xy + 4y = x,
over the interval (0, ∞).
16. Solve y 00 − y = ex by both the methods of undetermined coefficients and variation
of parameters. Explain any difference in the answers by two methods.
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