8.20 problem Exercise 21.27, page 231

Internal problem ID [4116]

Book: Ordinary Differential Equations, By Tenenbaum and Pollard. Dover, NY 1963
Section: Chapter 4. Higher order linear differential equations. Lesson 21. Undetermined Coefficients
Problem number: Exercise 21.27, page 231.
ODE order: 2.
ODE degree: 1.

CAS Maple gives this as type [[_2nd_order, _linear, _nonhomogeneous]]

\[ \boxed {y^{\prime \prime }+y-\sin \left (2 x \right ) \sin \left (x \right )=0} \]

Solution by Maple

Time used: 0.016 (sec). Leaf size: 25

dsolve(diff(y(x),x$2)+y(x)=sin(2*x)*sin(x),y(x), singsol=all)
 

\[ y \left (x \right ) = c_{2} \sin \left (x \right )+c_{1} \cos \left (x \right )+\frac {\sin \left (x \right ) \left (-\cos \left (x \right ) \sin \left (x \right )+x \right )}{4} \]

Solution by Mathematica

Time used: 0.014 (sec). Leaf size: 33

DSolve[y''[x]+y[x]==Sin[2*x]*Sin[x],y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to \frac {1}{16} (\cos (3 x)+(-1+16 c_1) \cos (x)+4 (x+4 c_2) \sin (x)) \\ \end{align*}