1.25.8 problem 8

Internal problem ID [628]
Book : Elementary Differential Equations. By C. Henry Edwards, David E. Penney and David Calvis. 6th edition. 2008
Section : Chapter 5. Linear systems of differential equations. Section 5.4 (The eigenvalue method for homogeneous systems). Problems at page 378
Problem number : 8
Date solved : Tuesday, September 30, 2025 at 04:04:42 AM
CAS classification : system_of_ODEs

\begin{align*} \frac {d}{d t}x_{1} \left (t \right )&=x_{1} \left (t \right )-5 x_{2} \left (t \right )\\ \frac {d}{d t}x_{2} \left (t \right )&=x_{1} \left (t \right )-x_{2} \left (t \right ) \end{align*}

✓ Maple. Time used: 0.133 (sec). Leaf size: 49

ode:=[diff(x__1(t),t) = x__1(t)-5*x__2(t), diff(x__2(t),t) = x__1(t)-x__2(t)]; 
dsolve(ode);
 

\begin{align*} x_{1} \left (t \right ) &= c_1 \sin \left (2 t \right )+c_2 \cos \left (2 t \right ) \\ x_{2} \left (t \right ) &= -\frac {2 c_1 \cos \left (2 t \right )}{5}+\frac {2 c_2 \sin \left (2 t \right )}{5}+\frac {c_1 \sin \left (2 t \right )}{5}+\frac {c_2 \cos \left (2 t \right )}{5} \\ \end{align*}

✓ Mathematica. Time used: 0.003 (sec). Leaf size: 48

ode={D[x1[t],t]==x1[t]-5*x2[t],D[x2[t],t]==x1[t]-x2[t]}; 
ic={}; 
DSolve[{ode,ic},{x1[t],x2[t]},t,IncludeSingularSolutions->True]
 

\begin{align*} \text {x1}(t)&\to c_1 \cos (2 t)+(c_1-5 c_2) \sin (t) \cos (t)\\ \text {x2}(t)&\to c_2 \cos (2 t)+(c_1-c_2) \sin (t) \cos (t) \end{align*}

✓ Sympy. Time used: 0.045 (sec). Leaf size: 37

from sympy import * 
t = symbols("t") 
x__1 = Function("x__1") 
x__2 = Function("x__2") 
ode=[Eq(-x__1(t) + 5*x__2(t) + Derivative(x__1(t), t),0),Eq(-x__1(t) + x__2(t) + Derivative(x__2(t), t),0)] 
ics = {} 
dsolve(ode,func=[x__1(t),x__2(t)],ics=ics)
 

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