Internal problem ID [368]
Book: Differential equations and linear algebra, 4th ed., Edwards and Penney
Section: Section 7.6, Multiple Eigenvalue Solutions. Page 451
Problem number: problem 11.
ODE order: 1.
ODE degree: 1.
Solve \begin {align*} x_{1}^{\prime }\left (t \right )&=-3 x_{1} \left (t \right )-4 x_{3} \left (t \right )\\ x_{2}^{\prime }\left (t \right )&=-x_{1} \left (t \right )-x_{2} \left (t \right )-x_{3} \left (t \right )\\ x_{3}^{\prime }\left (t \right )&=x_{1} \left (t \right )+x_{3} \left (t \right ) \end {align*}
✓ Solution by Maple
Time used: 0.031 (sec). Leaf size: 59
dsolve([diff(x__1(t),t)=-3*x__1(t)+0*x__2(t)-4*x__3(t),diff(x__2(t),t)=-1*x__1(t)-1*x__2(t)-1*x__3(t),diff(x__3(t),t)=1*x__1(t)+0*x__2(t)+1*x__3(t)],singsol=all)
\begin{align*} x_{1} \left (t \right ) &= {\mathrm e}^{-t} \left (c_{3} t +c_{2} \right ) \\ x_{2} \left (t \right ) &= \frac {\left (-c_{3} t^{2}-2 c_{2} t +c_{3} t +4 c_{1} \right ) {\mathrm e}^{-t}}{4} \\ x_{3} \left (t \right ) &= -\frac {{\mathrm e}^{-t} \left (2 c_{3} t +2 c_{2} +c_{3} \right )}{4} \\ \end{align*}
✓ Solution by Mathematica
Time used: 0.003 (sec). Leaf size: 81
DSolve[{x1'[t]==-3*x1[t]+0*x2[t]-4*x3[t],x2'[t]==-1*x1[t]-1*x2[t]-1*x3[t],x3'[t]==1*x1[t]+0*x2[t]+1*x3[t]},{x1[t],x2[t],x3[t]},t,IncludeSingularSolutions -> True]
\begin{align*} \text {x1}(t)\to e^{-t} (-2 c_1 t-4 c_3 t+c_1) \\ \text {x2}(t)\to \frac {1}{2} e^{-t} \left ((c_1+2 c_3) t^2-2 (c_1+c_3) t+2 c_2\right ) \\ \text {x3}(t)\to e^{-t} ((c_1+2 c_3) t+c_3) \\ \end{align*}