72.12.10 problem 18

Internal problem ID [14857]
Book : DIFFERENTIAL EQUATIONS by Paul Blanchard, Robert L. Devaney, Glen R. Hall. 4th edition. Brooks/Cole. Boston, USA. 2012
Section : Chapter 3. Linear Systems. Exercises section 3.5 page 327
Problem number : 18
Date solved : Tuesday, January 28, 2025 at 07:17:45 AM
CAS classification : system_of_ODEs

\begin{align*} x^{\prime }\left (t \right )&=2 x \left (t \right )+4 y\\ y^{\prime }&=3 x \left (t \right )+6 y \end{align*}

With initial conditions

\begin{align*} x \left (0\right ) = 1\\ y \left (0\right ) = 0 \end{align*}

✓ Solution by Maple

Time used: 0.046 (sec). Leaf size: 23

dsolve([diff(x(t),t) = 2*x(t)+4*y(t), diff(y(t),t) = 3*x(t)+6*y(t), x(0) = 1, y(0) = 0], singsol=all)
 

\begin{align*} x \left (t \right ) &= \frac {3}{4}+\frac {{\mathrm e}^{8 t}}{4} \\ y &= \frac {3 \,{\mathrm e}^{8 t}}{8}-\frac {3}{8} \\ \end{align*}

✓ Solution by Mathematica

Time used: 0.003 (sec). Leaf size: 30

DSolve[{D[x[t],t]==2*x[t]+4*y[t],D[y[t],t]==3*x[t]+6*y[t]},{x[0]==1,y[0]==0},{x[t],y[t]},t,IncludeSingularSolutions -> True]
 

\begin{align*} x(t)\to \frac {1}{4} \left (e^{8 t}+3\right ) \\ y(t)\to \frac {3}{8} \left (e^{8 t}-1\right ) \\ \end{align*}