Internal problem ID [9909]
Internal file name [OUTPUT/8856_Monday_June_06_2022_05_41_02_AM_89284024/index.tex]
Book: Differential Gleichungen, E. Kamke, 3rd ed. Chelsea Pub. NY, 1948
Section: Chapter 5, linear fifth and higher order
Problem number: 1587.
ODE order: 4.
ODE degree: 1.
The type(s) of ODE detected by this program : "unknown"
Maple gives the following as the ode type
[[_high_order, _with_linear_symmetries]]
Unable to solve or complete the solution.
\[ \boxed {x^{2} y^{\prime \prime \prime \prime }-a y=0} \] Unable to solve this ODE.
\[ \begin {array}{lll} & {} & \textrm {Let's solve}\hspace {3pt} \\ {} & {} & x^{2} \left (\frac {d}{d x}\frac {d}{d x}y^{\prime \prime }\right )-a y=0 \\ \bullet & {} & \textrm {Highest derivative means the order of the ODE is}\hspace {3pt} 4 \\ {} & {} & \frac {d}{d x}\frac {d}{d x}y^{\prime \prime } \\ \square & {} & \textrm {Check to see if}\hspace {3pt} x_{0}=0\hspace {3pt}\textrm {is a regular singular point}\hspace {3pt} \\ {} & \circ & \textrm {Define functions}\hspace {3pt} \\ {} & {} & \left [P_{2}\left (x \right )=0, P_{3}\left (x \right )=0, P_{4}\left (x \right )=0, P_{5}\left (x \right )=-\frac {a}{x^{2}}\right ] \\ {} & \circ & x \cdot P_{2}\left (x \right )\textrm {is analytic at}\hspace {3pt} x =0 \\ {} & {} & \left (x \cdot P_{2}\left (x \right )\right )\bigg | {\mstack {}{_{x \hiderel {=}0}}}=0 \\ {} & \circ & x^{2}\cdot P_{3}\left (x \right )\textrm {is analytic at}\hspace {3pt} x =0 \\ {} & {} & \left (x^{2}\cdot P_{3}\left (x \right )\right )\bigg | {\mstack {}{_{x \hiderel {=}0}}}=0 \\ {} & \circ & x^{3}\cdot P_{4}\left (x \right )\textrm {is analytic at}\hspace {3pt} x =0 \\ {} & {} & \left (x^{3}\cdot P_{4}\left (x \right )\right )\bigg | {\mstack {}{_{x \hiderel {=}0}}}=0 \\ {} & \circ & x^{4}\cdot P_{5}\left (x \right )\textrm {is analytic at}\hspace {3pt} x =0 \\ {} & {} & \left (x^{4}\cdot P_{5}\left (x \right )\right )\bigg | {\mstack {}{_{x \hiderel {=}0}}}=0 \\ {} & \circ & x =0\textrm {is a regular singular point}\hspace {3pt} \\ & {} & \textrm {Check to see if}\hspace {3pt} x_{0}=0\hspace {3pt}\textrm {is a regular singular point}\hspace {3pt} \\ {} & {} & x_{0}=0 \\ \bullet & {} & \textrm {Assume series solution for}\hspace {3pt} y \\ {} & {} & y=\moverset {\infty }{\munderset {k =0}{\sum }}a_{k} x^{k +r} \\ \square & {} & \textrm {Rewrite ODE with series expansions}\hspace {3pt} \\ {} & \circ & \textrm {Convert}\hspace {3pt} x^{2}\cdot \left (\frac {d}{d x}\frac {d}{d x}y^{\prime \prime }\right )\hspace {3pt}\textrm {to series expansion}\hspace {3pt} \\ {} & {} & x^{2}\cdot \left (\frac {d}{d x}\frac {d}{d x}y^{\prime \prime }\right )=\moverset {\infty }{\munderset {k =0}{\sum }}a_{k} \left (k +r \right ) \left (k +r -1\right ) \left (k +r -2\right ) \left (k +r -3\right ) x^{k +r -2} \\ {} & \circ & \textrm {Shift index using}\hspace {3pt} k \mathrm {->}k +2 \\ {} & {} & x^{2}\cdot \left (\frac {d}{d x}\frac {d}{d x}y^{\prime \prime }\right )=\moverset {\infty }{\munderset {k =-2}{\sum }}a_{k +2} \left (k +2+r \right ) \left (k +1+r \right ) \left (k +r \right ) \left (k +r -1\right ) x^{k +r} \\ & {} & \textrm {Rewrite ODE with series expansions}\hspace {3pt} \\ {} & {} & a_{0} r \left (-1+r \right ) \left (-2+r \right ) \left (-3+r \right ) x^{-2+r}+a_{1} \left (1+r \right ) r \left (-1+r \right ) \left (-2+r \right ) x^{-1+r}+\left (\moverset {\infty }{\munderset {k =0}{\sum }}\left (a_{k +2} \left (k +2+r \right ) \left (k +1+r \right ) \left (k +r \right ) \left (k +r -1\right )-a a_{k}\right ) x^{k +r}\right )=0 \\ \bullet & {} & a_{0}\textrm {cannot be 0 by assumption, giving the indicial equation}\hspace {3pt} \\ {} & {} & r \left (-1+r \right ) \left (-2+r \right ) \left (-3+r \right )=0 \\ \bullet & {} & \textrm {Values of r that satisfy the indicial equation}\hspace {3pt} \\ {} & {} & r \in \left \{0, 1, 2, 3\right \} \\ \bullet & {} & \textrm {Each term in the series must be 0, giving the recursion relation}\hspace {3pt} \\ {} & {} & a_{k +2} \left (k +2+r \right ) \left (k +1+r \right ) \left (k +r \right ) \left (k +r -1\right )-a a_{k}=0 \\ \bullet & {} & \textrm {Recursion relation that defines series solution to ODE}\hspace {3pt} \\ {} & {} & a_{k +2}=\frac {a a_{k}}{\left (k +2+r \right ) \left (k +1+r \right ) \left (k +r \right ) \left (k +r -1\right )} \\ \bullet & {} & \textrm {Recursion relation for}\hspace {3pt} r =0 \\ {} & {} & a_{k +2}=\frac {a a_{k}}{\left (k +2\right ) \left (k +1\right ) k \left (k -1\right )} \\ \bullet & {} & \textrm {Solution for}\hspace {3pt} r =0 \\ {} & {} & \left [y=\moverset {\infty }{\munderset {k =0}{\sum }}a_{k} x^{k}, a_{k +2}=\frac {a a_{k}}{\left (k +2\right ) \left (k +1\right ) k \left (k -1\right )}, 0=0\right ] \\ \bullet & {} & \textrm {Recursion relation for}\hspace {3pt} r =1 \\ {} & {} & a_{k +2}=\frac {a a_{k}}{\left (k +3\right ) \left (k +2\right ) \left (k +1\right ) k} \\ \bullet & {} & \textrm {Solution for}\hspace {3pt} r =1 \\ {} & {} & \left [y=\moverset {\infty }{\munderset {k =0}{\sum }}a_{k} x^{k +1}, a_{k +2}=\frac {a a_{k}}{\left (k +3\right ) \left (k +2\right ) \left (k +1\right ) k}, 0=0\right ] \\ \bullet & {} & \textrm {Recursion relation for}\hspace {3pt} r =2 \\ {} & {} & a_{k +2}=\frac {a a_{k}}{\left (k +4\right ) \left (k +3\right ) \left (k +2\right ) \left (k +1\right )} \\ \bullet & {} & \textrm {Solution for}\hspace {3pt} r =2 \\ {} & {} & \left [y=\moverset {\infty }{\munderset {k =0}{\sum }}a_{k} x^{k +2}, a_{k +2}=\frac {a a_{k}}{\left (k +4\right ) \left (k +3\right ) \left (k +2\right ) \left (k +1\right )}, 0=0\right ] \\ \bullet & {} & \textrm {Recursion relation for}\hspace {3pt} r =3 \\ {} & {} & a_{k +2}=\frac {a a_{k}}{\left (k +5\right ) \left (k +4\right ) \left (k +3\right ) \left (k +2\right )} \\ \bullet & {} & \textrm {Solution for}\hspace {3pt} r =3 \\ {} & {} & \left [y=\moverset {\infty }{\munderset {k =0}{\sum }}a_{k} x^{k +3}, a_{k +2}=\frac {a a_{k}}{\left (k +5\right ) \left (k +4\right ) \left (k +3\right ) \left (k +2\right )}, 24 a_{1}=0\right ] \\ \bullet & {} & \textrm {Combine solutions and rename parameters}\hspace {3pt} \\ {} & {} & \left [y=\left (\moverset {\infty }{\munderset {k =0}{\sum }}b_{k} x^{k}\right )+\left (\moverset {\infty }{\munderset {k =0}{\sum }}c_{k} x^{k +1}\right )+\left (\moverset {\infty }{\munderset {k =0}{\sum }}d_{k} x^{k +2}\right )+\left (\moverset {\infty }{\munderset {k =0}{\sum }}e_{k} x^{k +3}\right ), b_{k +2}=\frac {a b_{k}}{\left (k +2\right ) \left (k +1\right ) k \left (k -1\right )}, 0=0, c_{k +2}=\frac {a c_{k}}{\left (k +3\right ) \left (k +2\right ) \left (k +1\right ) k}, 0=0, d_{k +2}=\frac {a d_{k}}{\left (k +4\right ) \left (k +3\right ) \left (k +2\right ) \left (k +1\right )}, 0=0, e_{k +2}=\frac {a e_{k}}{\left (k +5\right ) \left (k +4\right ) \left (k +3\right ) \left (k +2\right )}, 24 e_{1}=0\right ] \end {array} \]
Maple trace
`Methods for high order ODEs: --- Trying classification methods --- trying a quadrature checking if the LODE has constant coefficients checking if the LODE is of Euler type trying high order exact linear fully integrable trying to convert to a linear ODE with constant coefficients trying differential order: 4; missing the dependent variable Multiplying solutions by`, exp(Int(-(1/2)/x, x))`Equation is the LCLM of 1/x*a^(1/2)*y(x)-diff(y(x),x)/x+diff(diff(y(x),x),x), -1/x* trying a quadrature checking if the LODE has constant coefficients checking if the LODE is of Euler type trying a symmetry of the form [xi=0, eta=F(x)] checking if the LODE is missing y -> Trying a Liouvillian solution using Kovacics algorithm <- No Liouvillian solutions exists -> Trying a solution in terms of special functions: -> Bessel <- Bessel successful <- special function solution successful trying a quadrature checking if the LODE has constant coefficients checking if the LODE is of Euler type trying a symmetry of the form [xi=0, eta=F(x)] checking if the LODE is missing y -> Trying a Liouvillian solution using Kovacics algorithm <- No Liouvillian solutions exists -> Trying a solution in terms of special functions: -> Bessel <- Bessel successful <- special function solution successful <- solving the LCLM ode successful `
✓ Solution by Maple
Time used: 0.031 (sec). Leaf size: 161
dsolve(x^2*diff(y(x),x$4)-a*y(x)=0,y(x), singsol=all)
\[ y \left (x \right ) = \frac {\left (\left (\operatorname {BesselY}\left (1, 2 \sqrt {-\sqrt {a}}\, \sqrt {x}\right ) c_{4} +\operatorname {BesselJ}\left (1, 2 \sqrt {-\sqrt {a}}\, \sqrt {x}\right ) c_{3} \right ) a^{\frac {1}{4}}+\left (\operatorname {BesselJ}\left (1, 2 a^{\frac {1}{4}} \sqrt {x}\right ) c_{1} +\operatorname {BesselY}\left (1, 2 a^{\frac {1}{4}} \sqrt {x}\right ) c_{2} \right ) \sqrt {-\sqrt {a}}\right ) \sqrt {x}-\left (\operatorname {BesselY}\left (0, 2 \sqrt {-\sqrt {a}}\, \sqrt {x}\right ) c_{4} +\operatorname {BesselJ}\left (0, 2 \sqrt {-\sqrt {a}}\, \sqrt {x}\right ) c_{3} +\operatorname {BesselY}\left (0, 2 a^{\frac {1}{4}} \sqrt {x}\right ) c_{2} +\operatorname {BesselJ}\left (0, 2 a^{\frac {1}{4}} \sqrt {x}\right ) c_{1} \right ) \sqrt {-\sqrt {a}}\, a^{\frac {1}{4}} x}{\sqrt {-\sqrt {a}}\, a^{\frac {1}{4}}} \]
✓ Solution by Mathematica
Time used: 0.052 (sec). Leaf size: 121
DSolve[x^2*y''''[x]-a*y[x]==0,y[x],x,IncludeSingularSolutions -> True]
\[ y(x)\to c_4 G_{0,4}^{2,0}\left (\frac {a x^2}{16}| \begin {array}{c} 0,1,\frac {1}{2},\frac {3}{2} \\ \end {array} \right )+c_2 G_{0,4}^{2,0}\left (\frac {a x^2}{16}| \begin {array}{c} \frac {1}{2},\frac {3}{2},0,1 \\ \end {array} \right )+\frac {1}{64} \sqrt {a} x \left ((4 c_3-3 i c_1) \operatorname {BesselJ}\left (2,2 \sqrt [4]{a} \sqrt {x}\right )+(3 i c_1+4 c_3) \operatorname {BesselI}\left (2,2 \sqrt [4]{a} \sqrt {x}\right )\right ) \]