21.1 problem 1(a)

Internal problem ID [11553]

Book: A First Course in Differential Equations by J. David Logan. Third Edition. Springer-Verlag, NY. 2015.
Section: Chapter 4, Linear Systems. Exercises page 225
Problem number: 1(a).
ODE order: 1.
ODE degree: 1.

Solve \begin {align*} x^{\prime }&=-3 x+y \left (t \right )\\ y^{\prime }\left (t \right )&=-3 y \left (t \right ) \end {align*}

Solution by Maple

Time used: 0.031 (sec). Leaf size: 24

dsolve([diff(x(t),t)=-3*x(t)+y(t),diff(y(t),t)=-3*y(t)],singsol=all)
 

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

Solution by Mathematica

Time used: 0.01 (sec). Leaf size: 29

DSolve[{x'[t]==-3*x[t]+y[t],y'[t]==-3*y[t]},{x[t],y[t]},t,IncludeSingularSolutions -> True]
 

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