16.11 problem 11

Internal problem ID [761]

Book: Elementary differential equations and boundary value problems, 10th ed., Boyce and DiPrima
Section: Chapter 7.6, Complex Eigenvalues. page 417
Problem number: 11.
ODE order: 1.
ODE degree: 1.

Solve \begin {align*} x_{1}^{\prime }\relax (t )&=\frac {3 x_{1} \relax (t )}{4}-2 x_{2} \relax (t )\\ x_{2}^{\prime }\relax (t )&=x_{1} \relax (t )-\frac {5 x_{2} \relax (t )}{4} \end {align*}

Solution by Maple

Time used: 0.047 (sec). Leaf size: 45

dsolve([diff(x__1(t),t)=3/4*x__1(t)-2*x__2(t),diff(x__2(t),t)=1*x__1(t)-5/4*x__2(t)],[x__1(t), x__2(t)], singsol=all)
 

\[ x_{1} \relax (t ) = {\mathrm e}^{-\frac {t}{4}} \left (\cos \relax (t ) c_{1}+c_{2} \cos \relax (t )+\sin \relax (t ) c_{1}-\sin \relax (t ) c_{2}\right ) \] \[ x_{2} \relax (t ) = {\mathrm e}^{-\frac {t}{4}} \left (\sin \relax (t ) c_{1}+c_{2} \cos \relax (t )\right ) \]

Solution by Mathematica

Time used: 0.006 (sec). Leaf size: 56

DSolve[{x1'[t]==3/4*x1[t]-2*x2[t],x2'[t]==1*x1[t]-5/4*x2[t]},{x1[t],x2[t]},t,IncludeSingularSolutions -> True]
 

\begin{align*} \text {x1}(t)\to e^{-t/4} (c_1 \cos (t)+(c_1-2 c_2) \sin (t)) \\ \text {x2}(t)\to e^{-t/4} (c_2 \cos (t)+(c_1-c_2) \sin (t)) \\ \end{align*}