44.29.2 problem 2(b)

Internal problem ID [9484]
Book : Differential Equations: Theory, Technique, and Practice by George Simmons, Steven Krantz. McGraw-Hill NY. 2007. 1st Edition.
Section : Chapter 10. Systems of First-Order Equations. Section A. Drill exercises. Page 400
Problem number : 2(b)
Date solved : Tuesday, September 30, 2025 at 06:19:21 PM
CAS classification : system_of_ODEs

\begin{align*} \frac {d}{d t}x \left (t \right )&=x \left (t \right )+y \left (t \right )\\ \frac {d}{d t}y \left (t \right )&=4 x \left (t \right )+y \left (t \right ) \end{align*}

✓ Maple. Time used: 0.110 (sec). Leaf size: 35

ode:=[diff(x(t),t) = x(t)+y(t), diff(y(t),t) = 4*x(t)+y(t)]; 
dsolve(ode);
 

\begin{align*} x \left (t \right ) &= c_1 \,{\mathrm e}^{3 t}+c_2 \,{\mathrm e}^{-t} \\ y \left (t \right ) &= 2 c_1 \,{\mathrm e}^{3 t}-2 c_2 \,{\mathrm e}^{-t} \\ \end{align*}

✓ Mathematica. Time used: 0.002 (sec). Leaf size: 70

ode={D[x[t],t]==x[t]+y[t],D[y[t],t]==4*x[t]+y[t]}; 
ic={}; 
DSolve[{ode,ic},{x[t],y[t]},t,IncludeSingularSolutions->True]
 

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

✓ Sympy. Time used: 0.051 (sec). Leaf size: 31

from sympy import * 
t = symbols("t") 
x = Function("x") 
y = Function("y") 
ode=[Eq(-x(t) - y(t) + Derivative(x(t), t),0),Eq(-4*x(t) - y(t) + Derivative(y(t), t),0)] 
ics = {} 
dsolve(ode,func=[x(t),y(t)],ics=ics)
 

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