Internal problem ID [1533]
Book: Elementary differential equations with boundary value problems. William F. Trench.
Brooks/Cole 2001
Section: Chapter 9 Introduction to Linear Higher Order Equations. Section 9.3. Undetermined
Coefficients for Higher Order Equations. Page 495
Problem number: section 9.3, problem 36.
ODE order: 3.
ODE degree: 1.
CAS Maple gives this as type [[_3rd_order, _missing_y]]
\[ \boxed {y^{\prime \prime \prime }-6 y^{\prime \prime }+18 y^{\prime }=-{\mathrm e}^{3 x} \left (\left (-3 x +2\right ) \cos \left (3 x \right )-\left (3+3 x \right ) \sin \left (3 x \right )\right )} \]
✓ Solution by Maple
Time used: 0.0 (sec). Leaf size: 46
dsolve(1*diff(y(x),x$3)-6*diff(y(x),x$2)+18*diff(y(x),x)-0*y(x)=-exp(3*x)*((2-3*x)*cos(3*x)-(3+3*x)*sin(3*x)),y(x), singsol=all)
\[ y \left (x \right ) = \frac {\left (\left (-3 x^{2}+6 c_{1} -6 c_{2} -1\right ) \cos \left (3 x \right )-3 \sin \left (3 x \right ) \left (x -2 c_{1} -2 c_{2} +\frac {1}{9}\right )\right ) {\mathrm e}^{3 x}}{36}+c_{3} \]
✓ Solution by Mathematica
Time used: 3.765 (sec). Leaf size: 57
DSolve[1*y'''[x]-6*y''[x]+18*y'[x]-0*y[x]==-Exp[3*x]*((2-3*x)*Cos[3*x]-(3+3*x)*Sin[3*x]),y[x],x,IncludeSingularSolutions -> True]
\[ y(x)\to c_3-\frac {1}{216} e^{3 x} \left (6 \left (3 x^2+1+6 c_1-6 c_2\right ) \cos (3 x)+(18 x+1-36 c_1-36 c_2) \sin (3 x)\right ) \]