Internal problem ID [1869]
Book: Differential equations and their applications, 4th ed., M. Braun
Section: Section 3.12, Systems of differential equations. The nonhomogeneous equation. variation of
parameters. Page 366
Problem number: 18.
ODE order: 1.
ODE degree: 1.
Solve \begin {align*} x_{1}^{\prime }\relax (t )&=3 x_{1}\relax (t )+2 x_{2}\relax (t )+4 x_{3}\relax (t )+2 \,{\mathrm e}^{8 t}\\ x_{2}^{\prime }\relax (t )&=2 x_{1}\relax (t )+2 x_{3}\relax (t )+{\mathrm e}^{8 t}\\ x_{3}^{\prime }\relax (t )&=4 x_{1}\relax (t )+2 x_{2}\relax (t )+3 x_{3}\relax (t )+2 \,{\mathrm e}^{8 t} \end {align*}
✓ Solution by Maple
Time used: 0.088 (sec). Leaf size: 86
dsolve([diff(x__1(t),t)=3*x__1(t)+2*x__2(t)+4*x__3(t)+2*exp(8*t),diff(x__2(t),t)=2*x__1(t)+0*x__2(t)+2*x__3(t)+exp(8*t),diff(x__3(t),t)=4*x__1(t)+2*x__2(t)+3*x__3(t)+2*exp(8*t)],[x__1(t), x__2(t), x__3(t)], singsol=all)
\[ x_{1}\relax (t ) = -\frac {5 c_{3} {\mathrm e}^{-t}}{4}+c_{2} {\mathrm e}^{8 t}+2 t \,{\mathrm e}^{8 t}-\frac {{\mathrm e}^{-t} c_{1}}{2} \] \[ x_{2}\relax (t ) = \frac {c_{3} {\mathrm e}^{-t}}{2}+\frac {c_{2} {\mathrm e}^{8 t}}{2}+t \,{\mathrm e}^{8 t}+{\mathrm e}^{-t} c_{1} \] \[ x_{3}\relax (t ) = c_{3} {\mathrm e}^{-t}+c_{2} {\mathrm e}^{8 t}+2 t \,{\mathrm e}^{8 t} \]
✓ Solution by Mathematica
Time used: 0.015 (sec). Leaf size: 139
DSolve[{x1'[t]==3*x1[t]+2*x2[t]+4*x3[t]+2*Exp[8*t],x2'[t]==2*x1[t]+0*x2[t]+2*x3[t]+Exp[8*t],x3'[t]==4*x1[t]+2*x2[t]+3*x3[t]+2*Exp[8*t]},{x1[t],x2[t],x3[t]},t,IncludeSingularSolutions -> True]
\begin{align*} \text {x1}(t)\to \frac {1}{9} e^{-t} \left (2 e^{9 t} (9 t+2 c_1+c_2+2 c_3)+5 c_1-2 (c_2+2 c_3)\right ) \\ \text {x2}(t)\to \frac {1}{9} e^{-t} \left (e^{9 t} (9 t+2 c_1+c_2+2 c_3)-2 (c_1-4 c_2+c_3)\right ) \\ \text {x3}(t)\to \frac {1}{9} e^{-t} \left (2 e^{9 t} (9 t+2 c_1+c_2+2 c_3)-4 c_1-2 c_2+5 c_3\right ) \\ \end{align*}