21.3 problem 3

21.3.1 Solving as riccati ode
21.3.2 Maple step by step solution

Internal problem ID [10637]
Internal file name [OUTPUT/9585_Monday_June_06_2022_03_10_59_PM_98380475/index.tex]

Book: Handbook of exact solutions for ordinary differential equations. By Polyanin and Zaitsev. Second edition
Section: Chapter 1, section 1.2. Riccati Equation. subsection 1.2.9. Some Transformations
Problem number: 3.
ODE order: 1.
ODE degree: 1.

The type(s) of ODE detected by this program : "riccati"

Maple gives the following as the ode type

[_Riccati]

\[ \boxed {y^{\prime }-y^{2}=\frac {f \left (\frac {a x +b}{c x +d}\right )}{\left (c x +d \right )^{4}}} \]

21.3.1 Solving as riccati ode

In canonical form the ODE is \begin {align*} y' &= F(x,y)\\ &= \frac {c^{4} x^{4} y^{2}+4 c^{3} d \,x^{3} y^{2}+6 c^{2} d^{2} x^{2} y^{2}+4 c \,d^{3} x \,y^{2}+d^{4} y^{2}+f \left (\frac {a x +b}{c x +d}\right )}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}} \end {align*}

This is a Riccati ODE. Comparing the ODE to solve \[ y' = \frac {c^{4} x^{4} y^{2}}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}}+\frac {4 c^{3} d \,x^{3} y^{2}}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}}+\frac {6 c^{2} d^{2} x^{2} y^{2}}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}}+\frac {4 c \,d^{3} x \,y^{2}}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}}+\frac {d^{4} y^{2}}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}}+\frac {f \left (\frac {a x +b}{c x +d}\right )}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}} \] With Riccati ODE standard form \[ y' = f_0(x)+ f_1(x)y+f_2(x)y^{2} \] Shows that \(f_0(x)=\frac {f \left (\frac {a x +b}{c x +d}\right )}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}}\), \(f_1(x)=0\) and \(f_2(x)=1\). Let \begin {align*} y &= \frac {-u'}{f_2 u} \\ &= \frac {-u'}{u} \tag {1} \end {align*}

Using the above substitution in the given ODE results (after some simplification)in a second order ODE to solve for \(u(x)\) which is \begin {align*} f_2 u''(x) -\left ( f_2' + f_1 f_2 \right ) u'(x) + f_2^2 f_0 u(x) &= 0 \tag {2} \end {align*}

But \begin {align*} f_2' &=0\\ f_1 f_2 &=0\\ f_2^2 f_0 &=\frac {f \left (\frac {a x +b}{c x +d}\right )}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}} \end {align*}

Substituting the above terms back in equation (2) gives \begin {align*} u^{\prime \prime }\left (x \right )+\frac {f \left (\frac {a x +b}{c x +d}\right ) u \left (x \right )}{c^{4} x^{4}+4 c^{3} d \,x^{3}+6 c^{2} d^{2} x^{2}+4 c \,d^{3} x +d^{4}} &=0 \end {align*}

Solving the above ODE (this ode solved using Maple, not this program), gives

\[ u \left (x \right ) = \operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right ) \] The above shows that \[ u^{\prime }\left (x \right ) = \frac {\partial }{\partial x}\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right ) \] Using the above in (1) gives the solution \[ y = -\frac {\frac {\partial }{\partial x}\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )}{\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )} \] Dividing both numerator and denominator by \(c_{1}\) gives, after renaming the constant \(\frac {c_{2}}{c_{1}}=c_{3}\) the following solution

\[ y = -\frac {\frac {\partial }{\partial x}\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )}{\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )} \]

Summary

The solution(s) found are the following \begin{align*} \tag{1} y &= -\frac {\frac {\partial }{\partial x}\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )}{\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )} \\ \end{align*}

Verification of solutions

\[ y = -\frac {\frac {\partial }{\partial x}\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )}{\operatorname {DESol}\left (\left \{\frac {f \left (\frac {a x +b}{c x +d}\right ) \textit {\_Y} \left (x \right )+\textit {\_Y}^{\prime \prime }\left (x \right ) \left (c x +d \right )^{4}}{\left (c x +d \right )^{4}}\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )} \] Verified OK.

21.3.2 Maple step by step solution

\[ \begin {array}{lll} & {} & \textrm {Let's solve}\hspace {3pt} \\ {} & {} & y^{2} c^{4} x^{4}-y^{\prime } c^{4} x^{4}+4 y^{2} c^{3} d \,x^{3}-4 y^{\prime } c^{3} d \,x^{3}+6 y^{2} c^{2} d^{2} x^{2}-6 y^{\prime } c^{2} d^{2} x^{2}+4 y^{2} c \,d^{3} x -4 y^{\prime } c \,d^{3} x +y^{2} d^{4}-y^{\prime } d^{4}+f \left (\frac {a x +b}{c x +d}\right )=0 \\ \bullet & {} & \textrm {Highest derivative means the order of the ODE is}\hspace {3pt} 1 \\ {} & {} & y^{\prime } \\ \bullet & {} & \textrm {Solve for the highest derivative}\hspace {3pt} \\ {} & {} & y^{\prime }=\frac {-y^{2} c^{4} x^{4}-4 y^{2} c^{3} d \,x^{3}-6 y^{2} c^{2} d^{2} x^{2}-4 y^{2} c \,d^{3} x -y^{2} d^{4}-f \left (\frac {a x +b}{c x +d}\right )}{-c^{4} x^{4}-4 c^{3} d \,x^{3}-6 c^{2} d^{2} x^{2}-4 c \,d^{3} x -d^{4}} \end {array} \]

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 inverse_Riccati 
trying 1st order ODE linearizable_by_differentiation 
--- Trying Lie symmetry methods, 1st order --- 
`, `-> Computing symmetries using: way = 4 
`, `-> Computing symmetries using: way = 2 
`, `-> Computing symmetries using: way = 6 
trying symmetry patterns for 1st order ODEs 
-> trying a symmetry pattern of the form [F(x)*G(y), 0] 
-> trying a symmetry pattern of the form [0, F(x)*G(y)] 
-> trying symmetry patterns of the forms [F(x),G(y)] and [G(y),F(x)] 
`, `-> Computing symmetries using: way = HINT 
   -> Calling odsolve with the ODE`, diff(y(x), x)-2*(2*c*d^3*x+y(x))/x, y(x)`      *** Sublevel 2 *** 
      Methods for first order ODEs: 
      --- Trying classification methods --- 
      trying a quadrature 
      trying 1st order linear 
      <- 1st order linear successful 
   -> Calling odsolve with the ODE`, diff(y(x), x)-2*(70*c*d^3*x+y(x))/x, y(x)`      *** Sublevel 2 *** 
      Methods for first order ODEs: 
      --- Trying classification methods --- 
      trying a quadrature 
      trying 1st order linear 
      <- 1st order linear successful 
   -> Calling odsolve with the ODE`, diff(y(x), x)-(35*c*d^3*x+2*y(x))/x, y(x)`      *** Sublevel 2 *** 
      Methods for first order ODEs: 
      --- Trying classification methods --- 
      trying a quadrature 
      trying 1st order linear 
      <- 1st order linear successful 
   -> Calling odsolve with the ODE`, diff(y(x), x)-(7*c*d^3*x+2*y(x))/x, y(x)`      *** Sublevel 2 *** 
      Methods for first order ODEs: 
      --- Trying classification methods --- 
      trying a quadrature 
      trying 1st order linear 
      <- 1st order linear successful 
   -> Calling odsolve with the ODE`, diff(y(x), x)-2*(7*c*d^3*x+y(x))/x, y(x)`      *** Sublevel 2 *** 
      Methods for first order ODEs: 
      --- Trying classification methods --- 
      trying a quadrature 
      trying 1st order linear 
      <- 1st order linear successful 
-> trying a symmetry pattern of the form [F(x),G(x)] 
-> trying a symmetry pattern of the form [F(y),G(y)] 
-> trying a symmetry pattern of the form [F(x)+G(y), 0] 
-> trying a symmetry pattern of the form [0, F(x)+G(y)] 
-> trying a symmetry pattern of the form [F(x),G(x)*y+H(x)] 
-> trying a symmetry pattern of conformal type`
 

Solution by Maple

dsolve(diff(y(x),x)=y(x)^2+1/(c*x+d)^4*f((a*x+b)/(c*x+d)),y(x), singsol=all)
 

\[ \text {No solution found} \]

Solution by Mathematica

Time used: 0.0 (sec). Leaf size: 0

DSolve[y'[x]==y[x]^2+1/(c*x+d)^4*f[(a*x+b)/(c*x+d)],y[x],x,IncludeSingularSolutions -> True]
 

Not solved