2.1.81 problem 80
Internal
problem
ID
[8219]
Book
:
Own
collection
of
miscellaneous
problems
Section
:
section
1.0
Problem
number
:
80
Date
solved
:
Tuesday, November 12, 2024 at 11:07:35 PM
CAS
classification
:
[[_Riccati, _special]]
Solve
\begin{align*} y^{\prime }&=x^{2}+y^{2} \end{align*}
Solved as first order ode of type reduced Riccati
Time used: 0.086 (sec)
This is reduced Riccati ode of the form
\begin{align*} y^{\prime }&=a \,x^{n}+b y^{2} \end{align*}
Comparing the given ode to the above shows that
\begin{align*} a &= 1\\ b &= 1\\ n &= 2 \end{align*}
Since \(n\neq -2\) then the solution of the reduced Riccati ode is given by
\begin{align*} w & =\sqrt {x}\left \{ \begin {array}[c]{cc} c_{1}\operatorname {BesselJ}\left ( \frac {1}{2k},\frac {1}{k}\sqrt {ab} x^{k}\right ) +c_{2}\operatorname {BesselY}\left ( \frac {1}{2k},\frac {1}{k}\sqrt {ab}x^{k}\right ) & ab>0\\ c_{1}\operatorname {BesselI}\left ( \frac {1}{2k},\frac {1}{k}\sqrt {-ab}x^{k}\right ) +c_{2}\operatorname {BesselK}\left ( \frac {1}{2k},\frac {1}{k}\sqrt {-ab}x^{k}\right ) & ab<0 \end {array} \right . \tag {1}\\ y & =-\frac {1}{b}\frac {w^{\prime }}{w}\nonumber \\ k &=1+\frac {n}{2}\nonumber \end{align*}
Since \(ab>0\) then EQ(1) gives
\begin{align*} k &= 2\\ w &= \sqrt {x}\, \left (c_1 \operatorname {BesselJ}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )+c_2 \operatorname {BesselY}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )\right ) \end{align*}
Therefore the solution becomes
\begin{align*} y & =-\frac {1}{b}\frac {w^{\prime }}{w} \end{align*}
Substituting the value of \(b,w\) found above and simplyfing gives
\[
y = \frac {\left (-\operatorname {BesselY}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right ) c_2 -\operatorname {BesselJ}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right ) c_1 \right ) x}{c_1 \operatorname {BesselJ}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )+c_2 \operatorname {BesselY}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )}
\]
Letting \(c_2 = 1\) the above becomes
\[
y = \frac {\left (-\operatorname {BesselY}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right )-\operatorname {BesselJ}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right ) c_1 \right ) x}{c_1 \operatorname {BesselJ}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )+\operatorname {BesselY}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )}
\]
Figure 2.164: Slope field plot
\(y^{\prime } = x^{2}+y^{2}\)
Summary of solutions found
\begin{align*}
y &= \frac {\left (-\operatorname {BesselY}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right )-\operatorname {BesselJ}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right ) c_1 \right ) x}{c_1 \operatorname {BesselJ}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )+\operatorname {BesselY}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )} \\
\end{align*}
Maple step by step solution
\[ \begin {array}{lll} & {} & \textrm {Let's solve}\hspace {3pt} \\ {} & {} & \frac {d}{d x}y \left (x \right )=x^{2}+y \left (x \right )^{2} \\ \bullet & {} & \textrm {Highest derivative means the order of the ODE is}\hspace {3pt} 1 \\ {} & {} & \frac {d}{d x}y \left (x \right ) \\ \bullet & {} & \textrm {Solve for the highest derivative}\hspace {3pt} \\ {} & {} & \frac {d}{d x}y \left (x \right )=x^{2}+y \left (x \right )^{2} \end {array} \]
Maple trace
` Methods for first order ODEs:
--- Trying classification methods ---
trying a quadrature
trying 1st order linear
trying Bernoulli
trying separable
trying inverse linear
trying homogeneous types:
trying Chini
differential order: 1; looking for linear symmetries
trying exact
Looking for potential symmetries
trying Riccati
trying Riccati Special
<- Riccati Special successful `
Maple dsolve solution
Solving time : 0.013
(sec)
Leaf size : 43
dsolve ( diff ( y ( x ), x ) = x^2+y(x)^2,
y(x),singsol=all)
\[
y = -\frac {x \left (\operatorname {BesselJ}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right ) c_{1} +\operatorname {BesselY}\left (-\frac {3}{4}, \frac {x^{2}}{2}\right )\right )}{c_{1} \operatorname {BesselJ}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )+\operatorname {BesselY}\left (\frac {1}{4}, \frac {x^{2}}{2}\right )}
\]
Mathematica DSolve solution
Solving time : 0.134
(sec)
Leaf size : 169
DSolve [{ D [ y [ x ], x ]== x ^2+ y [ x ]^2,{}},
y[x],x,IncludeSingularSolutions-> True ]
\begin{align*}
y(x)\to \frac {x^2 \left (-2 \operatorname {BesselJ}\left (-\frac {3}{4},\frac {x^2}{2}\right )+c_1 \left (\operatorname {BesselJ}\left (\frac {3}{4},\frac {x^2}{2}\right )-\operatorname {BesselJ}\left (-\frac {5}{4},\frac {x^2}{2}\right )\right )\right )-c_1 \operatorname {BesselJ}\left (-\frac {1}{4},\frac {x^2}{2}\right )}{2 x \left (\operatorname {BesselJ}\left (\frac {1}{4},\frac {x^2}{2}\right )+c_1 \operatorname {BesselJ}\left (-\frac {1}{4},\frac {x^2}{2}\right )\right )} \\
y(x)\to -\frac {x^2 \operatorname {BesselJ}\left (-\frac {5}{4},\frac {x^2}{2}\right )-x^2 \operatorname {BesselJ}\left (\frac {3}{4},\frac {x^2}{2}\right )+\operatorname {BesselJ}\left (-\frac {1}{4},\frac {x^2}{2}\right )}{2 x \operatorname {BesselJ}\left (-\frac {1}{4},\frac {x^2}{2}\right )} \\
\end{align*}