15.1 problem 28.2 (i)

Internal problem ID [11777]

Book: AN INTRODUCTION TO ORDINARY DIFFERENTIAL EQUATIONS by JAMES C. ROBINSON. Cambridge University Press 2004
Section: Chapter 28, Distinct real eigenvalues. Exercises page 282
Problem number: 28.2 (i).
ODE order: 1.
ODE degree: 1.

Solve \begin {align*} x^{\prime }\left (t \right )&=8 x \left (t \right )+14 y \left (t \right )\\ y^{\prime }\left (t \right )&=7 x \left (t \right )+y \left (t \right ) \end {align*}

Solution by Maple

Time used: 0.031 (sec). Leaf size: 36

dsolve([diff(x(t),t)=8*x(t)+14*y(t),diff(y(t),t)=7*x(t)+y(t)],[x(t), y(t)], singsol=all)
 

\[ x \left (t \right ) = 2 c_{1} {\mathrm e}^{15 t}-c_{2} {\mathrm e}^{-6 t} \] \[ y \left (t \right ) = c_{1} {\mathrm e}^{15 t}+c_{2} {\mathrm e}^{-6 t} \]

Solution by Mathematica

Time used: 0.005 (sec). Leaf size: 71

DSolve[{x'[t]==8*x[t]+14*y[t],y'[t]==7*x[t]+y[t]},{x[t],y[t]},t,IncludeSingularSolutions -> True]
 

\begin{align*} x(t)\to \frac {1}{3} e^{-6 t} \left (c_1 \left (2 e^{21 t}+1\right )+2 c_2 \left (e^{21 t}-1\right )\right ) y(t)\to \frac {1}{3} e^{-6 t} \left (c_1 \left (e^{21 t}-1\right )+c_2 \left (e^{21 t}+2\right )\right ) \end{align*}