21.7 problem section 10.4, problem 7

Internal problem ID [1595]

Book: Elementary differential equations with boundary value problems. William F. Trench. Brooks/Cole 2001
Section: Chapter 10 Linear system of Differential equations. Section 10.4, constant coefficient homogeneous system. Page 540
Problem number: section 10.4, problem 7.
ODE order: 1.
ODE degree: 1.

Solve \begin {align*} y_{1}^{\prime }\left (t \right )&=-6 y_{1} \left (t \right )-3 y_{2} \left (t \right )\\ y_{2}^{\prime }\left (t \right )&=y_{1} \left (t \right )-2 y_{2} \left (t \right ) \end {align*}

Solution by Maple

Time used: 0.015 (sec). Leaf size: 36

dsolve([diff(y__1(t),t)=-6*y__1(t)-3*y__2(t),diff(y__2(t),t)=1*y__1(t)-2*y__2(t)],singsol=all)
 

\begin{align*} y_{1} \left (t \right ) &= c_{1} {\mathrm e}^{-3 t}+c_{2} {\mathrm e}^{-5 t} \\ y_{2} \left (t \right ) &= -c_{1} {\mathrm e}^{-3 t}-\frac {c_{2} {\mathrm e}^{-5 t}}{3} \\ \end{align*}

Solution by Mathematica

Time used: 0.003 (sec). Leaf size: 72

DSolve[{y1'[t]==-6*y1[t]-3*y2[t],y2'[t]==1*y1[t]-2*y2[t]},{y1[t],y2[t]},t,IncludeSingularSolutions -> True]
                                                                                    
                                                                                    
 

\begin{align*} \text {y1}(t)\to \frac {1}{2} e^{-5 t} \left (-\left (c_1 \left (e^{2 t}-3\right )\right )-3 c_2 \left (e^{2 t}-1\right )\right ) \\ \text {y2}(t)\to \frac {1}{2} e^{-5 t} \left (c_1 \left (e^{2 t}-1\right )+c_2 \left (3 e^{2 t}-1\right )\right ) \\ \end{align*}