22.7 problem 4(g)

Internal problem ID [11561]

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(g).
ODE order: 1.
ODE degree: 1.

Solve \begin {align*} x^{\prime }&=5 x-4 y \left (t \right )\\ y^{\prime }\left (t \right )&=x+y \left (t \right ) \end {align*}

Solution by Maple

Time used: 0.016 (sec). Leaf size: 35

dsolve([diff(x(t),t)=5*x(t)-4*y(t),diff(y(t),t)=x(t)+y(t)],singsol=all)
 

\begin{align*} x \left (t \right ) &= {\mathrm e}^{3 t} \left (c_{2} t +c_{1} \right ) \\ y \left (t \right ) &= \frac {{\mathrm e}^{3 t} \left (2 c_{2} t +2 c_{1} -c_{2} \right )}{4} \\ \end{align*}

Solution by Mathematica

Time used: 0.004 (sec). Leaf size: 45

DSolve[{x'[t]==5*x[t]-4*y[t],y'[t]==x[t]+y[t]},{x[t],y[t]},t,IncludeSingularSolutions -> True]
 

\begin{align*} x(t)\to e^{3 t} (2 c_1 t-4 c_2 t+c_1) \\ y(t)\to e^{3 t} ((c_1-2 c_2) t+c_2) \\ \end{align*}