73.22.15 problem 31.7 (h)

Internal problem ID [15571]
Book : Ordinary Differential Equations. An introduction to the fundamentals. Kenneth B. Howell. second edition. CRC Press. FL, USA. 2020
Section : Chapter 31. Delta Functions. Additional Exercises. page 572
Problem number : 31.7 (h)
Date solved : Monday, March 31, 2025 at 01:41:26 PM
CAS classification : [[_2nd_order, _linear, _nonhomogeneous]]

\begin{align*} y^{\prime \prime }+4 y^{\prime }-12 y&=\delta \left (t -3\right ) \end{align*}

Using Laplace method With initial conditions

\begin{align*} y \left (0\right )&=0\\ y^{\prime }\left (0\right )&=0 \end{align*}

✓ Maple. Time used: 0.106 (sec). Leaf size: 22

ode:=diff(diff(y(t),t),t)+4*diff(y(t),t)-12*y(t) = Dirac(t-3); 
ic:=y(0) = 0, D(y)(0) = 0; 
dsolve([ode,ic],y(t),method='laplace');
 

\[ y = \frac {\operatorname {Heaviside}\left (t -3\right ) \sinh \left (-12+4 t \right ) {\mathrm e}^{6-2 t}}{4} \]

✓ Mathematica. Time used: 0.031 (sec). Leaf size: 104

ode=D[y[t],{t,2}]+4*D[y[t],t]-12*y[t]==DiracDelta[t-3]; 
ic={y[0]==0,Derivative[1][y][0] ==0}; 
DSolve[{ode,ic},y[t],t,IncludeSingularSolutions->True]
 

\[ y(t)\to -e^{-6 t} \left (-\int _1^t-\frac {1}{8} e^{18} \delta (K[1]-3)dK[1]+e^{8 t} \int _1^0\frac {\delta (K[2]-3)}{8 e^6}dK[2]-e^{8 t} \int _1^t\frac {\delta (K[2]-3)}{8 e^6}dK[2]+\int _1^0-\frac {1}{8} e^{18} \delta (K[1]-3)dK[1]\right ) \]

✓ Sympy. Time used: 0.950 (sec). Leaf size: 66

from sympy import * 
t = symbols("t") 
y = Function("y") 
ode = Eq(-Dirac(t - 3) - 12*y(t) + 4*Derivative(y(t), t) + Derivative(y(t), (t, 2)),0) 
ics = {y(0): 0, Subs(Derivative(y(t), t), t, 0): 0} 
dsolve(ode,func=y(t),ics=ics)
 

\[ y{\left (t \right )} = \left (\frac {\int \operatorname {Dirac}{\left (t - 3 \right )} e^{- 2 t}\, dt}{8} - \frac {\int \limits ^{0} \operatorname {Dirac}{\left (t - 3 \right )} e^{- 2 t}\, dt}{8}\right ) e^{2 t} + \left (- \frac {\int \operatorname {Dirac}{\left (t - 3 \right )} e^{6 t}\, dt}{8} + \frac {\int \limits ^{0} \operatorname {Dirac}{\left (t - 3 \right )} e^{6 t}\, dt}{8}\right ) e^{- 6 t} \]