72.5.27 problem 23

Internal problem ID [14634]
Book : DIFFERENTIAL EQUATIONS by Paul Blanchard, Robert L. Devaney, Glen R. Hall. 4th edition. Brooks/Cole. Boston, USA. 2012
Section : Chapter 1. First-Order Differential Equations. Exercises section 1.6 page 89
Problem number : 23
Date solved : Thursday, March 13, 2025 at 04:11:17 AM
CAS classification : [_quadrature]

\begin{align*} y^{\prime }&=y^{2}-4 y+2 \end{align*}

With initial conditions

\begin{align*} y \left (0\right )&=2 \end{align*}

✓ Maple. Time used: 0.065 (sec). Leaf size: 17

ode:=diff(y(t),t) = y(t)^2-4*y(t)+2; 
ic:=y(0) = 2; 
dsolve([ode,ic],y(t), singsol=all);
 

\[ y = 2-\sqrt {2}\, \tanh \left (\sqrt {2}\, t \right ) \]

✓ Mathematica. Time used: 0.023 (sec). Leaf size: 46

ode=D[y[t],t]==y[t]^2-4*y[t]+2; 
ic={y[0]==2}; 
DSolve[{ode,ic},y[t],t,IncludeSingularSolutions->True]
 

\[ y(t)\to \frac {-\left (\sqrt {2}-2\right ) e^{2 \sqrt {2} t}+2+\sqrt {2}}{e^{2 \sqrt {2} t}+1} \]

✓ Sympy. Time used: 0.458 (sec). Leaf size: 49

from sympy import * 
t = symbols("t") 
y = Function("y") 
ode = Eq(-y(t)**2 + 4*y(t) + Derivative(y(t), t) - 2,0) 
ics = {y(0): 2} 
dsolve(ode,func=y(t),ics=ics)
 

\[ t - \frac {\sqrt {2} \log {\left (y{\left (t \right )} - 2 - \sqrt {2} \right )}}{4} + \frac {\sqrt {2} \log {\left (y{\left (t \right )} - 2 + \sqrt {2} \right )}}{4} = - \frac {\sqrt {2} i \pi }{4} \]