89.15.12 problem 12

Internal problem ID [24646]
Book : A short course in Differential Equations. Earl D. Rainville. Second edition. 1958. Macmillan Publisher, NY. CAT 58-5010
Section : Chapter 9. Nonhomogeneous Equations: Undetermined coefficients. Oral Exercises at page 131
Problem number : 12
Date solved : Thursday, October 02, 2025 at 10:46:42 PM
CAS classification : [[_high_order, _missing_x]]

\begin{align*} y^{\prime \prime \prime \prime }+9 y^{\prime \prime \prime }&=11 \end{align*}

✓ Maple. Time used: 0.001 (sec). Leaf size: 27

ode:=diff(diff(diff(diff(y(x),x),x),x),x)+9*diff(diff(diff(y(x),x),x),x) = 11; 
dsolve(ode,y(x), singsol=all);
 

\[ y = \frac {11 x^{3}}{54}+\frac {c_2 \,x^{2}}{2}-\frac {{\mathrm e}^{-9 x} c_1}{729}+c_3 x +c_4 \]

✓ Mathematica. Time used: 0.023 (sec). Leaf size: 36

ode=D[y[x],{x,4}]+9*D[y[x],{x,3}]==11; 
ic={}; 
DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
 

\begin{align*} y(x)&\to \frac {11 x^3}{54}+c_4 x^2+c_3 x-\frac {1}{729} c_1 e^{-9 x}+c_2 \end{align*}

✓ Sympy. Time used: 0.066 (sec). Leaf size: 26

from sympy import * 
x = symbols("x") 
y = Function("y") 
ode = Eq(9*Derivative(y(x), (x, 3)) + Derivative(y(x), (x, 4)) - 11,0) 
ics = {} 
dsolve(ode,func=y(x),ics=ics)
 

\[ y{\left (x \right )} = C_{1} + C_{2} x + C_{3} x^{2} + C_{4} e^{- 9 x} + \frac {11 x^{3}}{54} \]