9.4.14 problem problem 14

Internal problem ID [978]
Book : Differential equations and linear algebra, 4th ed., Edwards and Penney
Section : Section 7.3, The eigenvalue method for linear systems. Page 395
Problem number : problem 14
Date solved : Tuesday, March 04, 2025 at 12:06:44 PM
CAS classification : system_of_ODEs

\begin{align*} \frac {d}{d t}x_{1} \left (t \right )&=3 x_{1} \left (t \right )-4 x_{2} \left (t \right )\\ \frac {d}{d t}x_{2} \left (t \right )&=4 x_{1} \left (t \right )+3 x_{2} \left (t \right ) \end{align*}

✓ Maple. Time used: 0.006 (sec). Leaf size: 45

ode:=[diff(x__1(t),t) = 3*x__1(t)-4*x__2(t), diff(x__2(t),t) = 4*x__1(t)+3*x__2(t)]; 
dsolve(ode);
 

\begin{align*} x_{1} \left (t \right ) &= {\mathrm e}^{3 t} \left (c_1 \sin \left (4 t \right )+c_2 \cos \left (4 t \right )\right ) \\ x_{2} \left (t \right ) &= -{\mathrm e}^{3 t} \left (c_1 \cos \left (4 t \right )-c_2 \sin \left (4 t \right )\right ) \\ \end{align*}

✓ Mathematica. Time used: 0.002 (sec). Leaf size: 51

ode={D[ x1[t],t]==3*x1[t]-4*x2[t],D[ x2[t],t]==4*x1[t]+3*x2[t]}; 
ic={}; 
DSolve[{ode,ic},{x1[t],x2[t]},t,IncludeSingularSolutions->True]
 

\begin{align*} \text {x1}(t)\to e^{3 t} (c_1 \cos (4 t)-c_2 \sin (4 t)) \\ \text {x2}(t)\to e^{3 t} (c_2 \cos (4 t)+c_1 \sin (4 t)) \\ \end{align*}

✓ Sympy. Time used: 0.110 (sec). Leaf size: 53

from sympy import * 
t = symbols("t") 
x__1 = Function("x__1") 
x__2 = Function("x__2") 
ode=[Eq(-3*x__1(t) + 4*x__2(t) + Derivative(x__1(t), t),0),Eq(-4*x__1(t) - 3*x__2(t) + Derivative(x__2(t), t),0)] 
ics = {} 
dsolve(ode,func=[x__1(t),x__2(t)],ics=ics)
 

\[ \left [ x^{1}{\left (t \right )} = - C_{1} e^{3 t} \sin {\left (4 t \right )} - C_{2} e^{3 t} \cos {\left (4 t \right )}, \ x^{2}{\left (t \right )} = C_{1} e^{3 t} \cos {\left (4 t \right )} - C_{2} e^{3 t} \sin {\left (4 t \right )}\right ] \]