9.46 problem 1901

Internal problem ID [9480]

Book: Differential Gleichungen, E. Kamke, 3rd ed. Chelsea Pub. NY, 1948
Section: Chapter 8, system of first order odes
Problem number: 1901.
ODE order: 1.
ODE degree: 1.

Solve \begin {align*} x^{\prime }\relax (t )&=y \relax (t )-z \relax (t )\\ y^{\prime }\relax (t )&=x \relax (t )+y \relax (t )\\ z^{\prime }\relax (t )&=x \relax (t )+z \relax (t ) \end {align*}

Solution by Maple

Time used: 0.203 (sec). Leaf size: 48

dsolve({diff(x(t),t)=y(t)-z(t),diff(y(t),t)=x(t)+y(t),diff(z(t),t)=x(t)+z(t)},{x(t), y(t), z(t)}, singsol=all)
 

\[ x \relax (t ) = c_{2}+c_{3} {\mathrm e}^{t} \] \[ y \relax (t ) = c_{3} t \,{\mathrm e}^{t}+c_{1} {\mathrm e}^{t}-c_{2} \] \[ z \relax (t ) = c_{3} t \,{\mathrm e}^{t}+c_{1} {\mathrm e}^{t}-c_{3} {\mathrm e}^{t}-c_{2} \]

Solution by Mathematica

Time used: 0.005 (sec). Leaf size: 87

DSolve[{x'[t]==y[t]-z[t],y'[t]==x[t]+y[t],z'[t]==x[t]+z[t]},{x[t],y[t],z[t]},t,IncludeSingularSolutions -> True]
 

\begin{align*} x(t)\to (c_2-c_3) \left (e^t-1\right )+c_1 \\ y(t)\to e^t ((c_2-c_3) t+c_1+c_3)-c_1+c_2-c_3 \\ z(t)\to e^t (c_2 (t-1)-c_3 (t-2)+c_1)-c_1+c_2-c_3 \\ \end{align*}