15.12 problem Problem 12

Internal problem ID [2386]

Book: Differential equations and linear algebra, Stephen W. Goode and Scott A Annin. Fourth edition, 2015
Section: Chapter 10, The Laplace Transform and Some Elementary Applications. Exercises for 10.8. page 710
Problem number: Problem 12.
ODE order: 2.
ODE degree: 1.

CAS Maple gives this as type [[_2nd_order, _linear, _nonhomogeneous]]

\[ \boxed {y^{\prime \prime }+16 y-4 \cos \left (3 t \right )-\left (\delta \left (t -\frac {\pi }{3}\right )\right )=0} \] With initial conditions \begin {align*} [y \left (0\right ) = 0, y^{\prime }\left (0\right ) = 0] \end {align*}

Solution by Maple

Time used: 0.078 (sec). Leaf size: 40

dsolve([diff(y(t),t$2)+16*y(t)=4*cos(3*t)+Dirac(t-Pi/3),y(0) = 0, D(y)(0) = 0],y(t), singsol=all)
 

\[ y \left (t \right ) = -\frac {4 \cos \left (4 t \right )}{7}+\frac {\left (\sqrt {3}\, \cos \left (4 t \right )-\sin \left (4 t \right )\right ) \operatorname {Heaviside}\left (t -\frac {\pi }{3}\right )}{8}+\frac {4 \cos \left (3 t \right )}{7} \]

Solution by Mathematica

Time used: 0.088 (sec). Leaf size: 50

DSolve[{y''[t]+16*y[t]==4*Cos[3*t]+DiracDelta[t-Pi/3],{y[0]==0,y'[0]==0}},y[t],t,IncludeSingularSolutions -> True]
 

\begin{align*} y(t)\to \frac {1}{8} \theta (3 t-\pi ) \left (\sqrt {3} \cos (4 t)-\sin (4 t)\right )+\frac {4}{7} (\cos (3 t)-\cos (4 t)) \\ \end{align*}