90.31.21 problem 24

Internal problem ID [25471]
Book : Ordinary Differential Equations. By William Adkins and Mark G Davidson. Springer. NY. 2010. ISBN 978-1-4614-3617-1
Section : Chapter 7. Power series methods. Exercises at page 537
Problem number : 24
Date solved : Friday, October 03, 2025 at 12:01:53 AM
CAS classification : [[_2nd_order, _with_linear_symmetries]]

\begin{align*} t^{2} y^{\prime \prime }+t \left (t +1\right ) y^{\prime }-y&=0 \end{align*}

Using series method with expansion around

\begin{align*} 0 \end{align*}

✓ Maple. Time used: 0.008 (sec). Leaf size: 45

Order:=6; 
ode:=t^2*diff(diff(y(t),t),t)+t*(t+1)*diff(y(t),t)-y(t) = 0; 
dsolve(ode,y(t),type='series',t=0);
 

\[ y = c_1 t \left (1-\frac {1}{3} t +\frac {1}{12} t^{2}-\frac {1}{60} t^{3}+\frac {1}{360} t^{4}-\frac {1}{2520} t^{5}+\operatorname {O}\left (t^{6}\right )\right )+\frac {c_2 \left (-2+2 t -t^{2}+\frac {1}{3} t^{3}-\frac {1}{12} t^{4}+\frac {1}{60} t^{5}+\operatorname {O}\left (t^{6}\right )\right )}{t} \]

✓ Mathematica. Time used: 0.01 (sec). Leaf size: 64

ode=t^2*D[y[t],{t,2}]+t*(1+t)*D[y[t],t]-y[t]==0; 
ic={}; 
AsymptoticDSolveValue[{ode,ic},y[t],{t,0,5}]
 

\[ y(t)\to c_1 \left (\frac {t^3}{24}-\frac {t^2}{6}+\frac {t}{2}+\frac {1}{t}-1\right )+c_2 \left (\frac {t^5}{360}-\frac {t^4}{60}+\frac {t^3}{12}-\frac {t^2}{3}+t\right ) \]

✓ Sympy. Time used: 0.299 (sec). Leaf size: 29

from sympy import * 
t = symbols("t") 
y = Function("y") 
ode = Eq(t**2*Derivative(y(t), (t, 2)) + t*(t + 1)*Derivative(y(t), (t, 2)) - y(t),0) 
ics = {} 
dsolve(ode,func=y(t),ics=ics,hint="2nd_power_series_regular",x0=0,n=6)
 

\[ y{\left (t \right )} = C_{1} t \left (\frac {t^{4}}{2880} + \frac {t^{3}}{144} + \frac {t^{2}}{12} + \frac {t}{2} + 1\right ) + O\left (t^{6}\right ) \]