63.22.3 problem 4(c)

Internal problem ID [13154]
Book : A First Course in Differential Equations by J. David Logan. Third Edition. Springer-Verlag, NY. 2015.
Section : Chapter 4, Linear Systems. Exercises page 237
Problem number : 4(c)
Date solved : Wednesday, March 05, 2025 at 09:18:23 PM
CAS classification : system_of_ODEs

\begin{align*} \frac {d}{d t}x \left (t \right )&=2 x \left (t \right )+2 y \left (t \right )\\ \frac {d}{d t}y \left (t \right )&=6 x \left (t \right )+3 y \left (t \right ) \end{align*}

✓ Maple. Time used: 0.039 (sec). Leaf size: 35

ode:=[diff(x(t),t) = 2*x(t)+2*y(t), diff(y(t),t) = 6*x(t)+3*y(t)]; 
dsolve(ode);
 

\begin{align*} x \left (t \right ) &= {\mathrm e}^{-t} c_{1} +c_{2} {\mathrm e}^{6 t} \\ y &= -\frac {3 \,{\mathrm e}^{-t} c_{1}}{2}+2 c_{2} {\mathrm e}^{6 t} \\ \end{align*}

✓ Mathematica. Time used: 0.005 (sec). Leaf size: 74

ode={D[x[t],t]==2*x[t]+2*y[t],D[y[t],t]==6*x[t]+3*y[t]}; 
ic={}; 
DSolve[{ode,ic},{x[t],y[t]},t,IncludeSingularSolutions->True]
 

\begin{align*} x(t)\to \frac {1}{7} e^{-t} \left (c_1 \left (3 e^{7 t}+4\right )+2 c_2 \left (e^{7 t}-1\right )\right ) \\ y(t)\to \frac {1}{7} e^{-t} \left (6 c_1 \left (e^{7 t}-1\right )+c_2 \left (4 e^{7 t}+3\right )\right ) \\ \end{align*}

✓ Sympy. Time used: 0.099 (sec). Leaf size: 32

from sympy import * 
t = symbols("t") 
x = Function("x") 
y = Function("y") 
ode=[Eq(-2*x(t) - 2*y(t) + Derivative(x(t), t),0),Eq(-6*x(t) - 3*y(t) + Derivative(y(t), t),0)] 
ics = {} 
dsolve(ode,func=[x(t),y(t)],ics=ics)
 

\[ \left [ x{\left (t \right )} = - \frac {2 C_{1} e^{- t}}{3} + \frac {C_{2} e^{6 t}}{2}, \ y{\left (t \right )} = C_{1} e^{- t} + C_{2} e^{6 t}\right ] \]