46.1.25 problem 23

Internal problem ID [9528]
Book : DIFFERENTIAL EQUATIONS with Boundary Value Problems. DENNIS G. ZILL, WARREN S. WRIGHT, MICHAEL R. CULLEN. Brooks/Cole. Boston, MA. 2013. 8th edition.
Section : CHAPTER 6 SERIES SOLUTIONS OF LINEAR EQUATIONS. Section 6.2 SOLUTIONS ABOUT ORDINARY POINTS. EXERCISES 6.2. Page 246
Problem number : 23
Date solved : Tuesday, September 30, 2025 at 06:20:05 PM
CAS classification : [[_2nd_order, _with_linear_symmetries]]

\begin{align*} y^{\prime \prime }+\sin \left (x \right ) y&=0 \end{align*}

Using series method with expansion around

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

✓ Maple. Time used: 0.009 (sec). Leaf size: 54

Order:=8; 
ode:=diff(diff(y(x),x),x)+sin(x)*y(x) = 0; 
dsolve(ode,y(x),type='series',x=0);
 

\[ y = \left (1-\frac {1}{6} x^{3}+\frac {1}{120} x^{5}+\frac {1}{180} x^{6}-\frac {1}{5040} x^{7}\right ) y \left (0\right )+\left (x -\frac {1}{12} x^{4}+\frac {1}{180} x^{6}+\frac {1}{504} x^{7}\right ) y^{\prime }\left (0\right )+O\left (x^{8}\right ) \]

✓ Mathematica. Time used: 0.001 (sec). Leaf size: 63

ode=D[y[x],{x,2}]+Sin[x]*y[x]==0; 
ic={}; 
AsymptoticDSolveValue[{ode,ic},y[x],{x,0,7}]
 

\[ y(x)\to c_2 \left (\frac {x^7}{504}+\frac {x^6}{180}-\frac {x^4}{12}+x\right )+c_1 \left (-\frac {x^7}{5040}+\frac {x^6}{180}+\frac {x^5}{120}-\frac {x^3}{6}+1\right ) \]

✓ Sympy. Time used: 1.196 (sec). Leaf size: 61

from sympy import * 
x = symbols("x") 
y = Function("y") 
ode = Eq(y(x)*sin(x) + Derivative(y(x), (x, 2)),0) 
ics = {} 
dsolve(ode,func=y(x),ics=ics,hint="2nd_power_series_ordinary",x0=0,n=8)
 

\[ y{\left (x \right )} = C_{2} \left (- \frac {x^{6} \sin ^{3}{\left (x \right )}}{720} + \frac {x^{4} \sin ^{2}{\left (x \right )}}{24} - \frac {x^{2} \sin {\left (x \right )}}{2} + 1\right ) + C_{1} x \left (\frac {x^{4} \sin ^{2}{\left (x \right )}}{120} - \frac {x^{2} \sin {\left (x \right )}}{6} + 1\right ) + O\left (x^{8}\right ) \]