28.8 problem 1(h)

Internal problem ID [6527]

Book: Differential Equations: Theory, Technique, and Practice by George Simmons, Steven Krantz. McGraw-Hill NY. 2007. 1st Edition.
Section: Chapter 10. Systems of First-Order Equations. Section 10.3 Homogeneous Linear Systems with Constant Coefficients. Page 387
Problem number: 1(h).
ODE order: 1.
ODE degree: 1.

Solve \begin {align*} x^{\prime }\left (t \right )&=x \left (t \right )-2 y \left (t \right )\\ y^{\prime }\left (t \right )&=4 x \left (t \right )+5 y \left (t \right ) \end {align*}

Solution by Maple

Time used: 0.031 (sec). Leaf size: 58

dsolve([diff(x(t),t)=x(t)-2*y(t),diff(y(t),t)=4*x(t)+5*y(t)],[x(t), y(t)], singsol=all)
 

\[ x \left (t \right ) = -\frac {{\mathrm e}^{3 t} \left (\sin \left (2 t \right ) c_{1} +\sin \left (2 t \right ) c_{2} -\cos \left (2 t \right ) c_{1} +\cos \left (2 t \right ) c_{2} \right )}{2} \] \[ y \left (t \right ) = {\mathrm e}^{3 t} \left (\sin \left (2 t \right ) c_{1} +\cos \left (2 t \right ) c_{2} \right ) \]

Solution by Mathematica

Time used: 0.005 (sec). Leaf size: 59

DSolve[{x'[t]==x[t]-2*y[t],y'[t]==4*x[t]+5*y[t]},{x[t],y[t]},t,IncludeSingularSolutions -> True]
 

\begin{align*} x(t)\to e^{3 t} (c_1 \cos (2 t)-(c_1+c_2) \sin (2 t)) y(t)\to e^{3 t} (c_2 \cos (2 t)+(2 c_1+c_2) \sin (2 t)) \end{align*}