26.9.15 problem Exercise 22.15, page 240

Internal problem ID [7124]
Book : Ordinary Differential Equations, By Tenenbaum and Pollard. Dover, NY 1963
Section : Chapter 4. Higher order linear differential equations. Lesson 22. Variation of Parameters
Problem number : Exercise 22.15, page 240
Date solved : Tuesday, September 30, 2025 at 04:21:44 PM
CAS classification : [[_2nd_order, _linear, _nonhomogeneous]]

\begin{align*} y^{\prime \prime }-3 y^{\prime }+2 y&=\cos \left ({\mathrm e}^{-x}\right ) \end{align*}

✓ Maple. Time used: 0.002 (sec). Leaf size: 22

ode:=diff(diff(y(x),x),x)-3*diff(y(x),x)+2*y(x) = cos(exp(-x)); 
dsolve(ode,y(x), singsol=all);
 

\[ y = {\mathrm e}^{x} \left (\left (-\cos \left ({\mathrm e}^{-x}\right )+c_1 -1\right ) {\mathrm e}^{x}+c_2 \right ) \]

✓ Mathematica. Time used: 0.054 (sec). Leaf size: 65

ode=D[y[x],{x,2}]-3*D[y[x],x]+2*y[x]==Cos[Exp[-x]]; 
ic={}; 
DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
 

\begin{align*} y(x)&\to e^x \left (\int _1^x-e^{-K[1]} \cos \left (e^{-K[1]}\right )dK[1]+e^x \int _1^xe^{-2 K[2]} \cos \left (e^{-K[2]}\right )dK[2]+c_2 e^x+c_1\right ) \end{align*}

✓ Sympy. Time used: 2.812 (sec). Leaf size: 19

from sympy import * 
x = symbols("x") 
y = Function("y") 
ode = Eq(2*y(x) - cos(exp(-x)) - 3*Derivative(y(x), x) + Derivative(y(x), (x, 2)),0) 
ics = {} 
dsolve(ode,func=y(x),ics=ics)
 

\[ y{\left (x \right )} = \left (C_{1} + \left (C_{2} - \cos {\left (e^{- x} \right )}\right ) e^{x}\right ) e^{x} \]