87.21.14 problem 14

Internal problem ID [23728]
Book : Ordinary differential equations with modern applications. Ladas, G. E. and Finizio, N. Wadsworth Publishing. California. 1978. ISBN 0-534-00552-7. QA372.F56
Section : Chapter 3. Linear Systems. Exercise at page 178
Problem number : 14
Date solved : Thursday, October 02, 2025 at 09:44:39 PM
CAS classification : system_of_ODEs

\begin{align*} x^{\prime }&=-y \left (t \right )\\ y^{\prime }\left (t \right )&=x-2 y \left (t \right ) \end{align*}

✓ Maple. Time used: 0.044 (sec). Leaf size: 30

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

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

✓ Mathematica. Time used: 0.002 (sec). Leaf size: 44

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

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

✓ Sympy. Time used: 0.069 (sec). Leaf size: 29

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

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