2.1.51 Problem 51

Solved as second order missing x ode
Maple
Mathematica
Sympy

Internal problem ID [9122]
Book : Second order enumerated odes
Section : section 1
Problem number : 51
Date solved : Wednesday, March 05, 2025 at 07:26:17 AM
CAS classification : [[_2nd_order, _missing_x]]

Solve

yy3+y3y=0

Factoring the ode gives these factors

(1)y=0(2)y3+y2y=0

Now each of the above equations is solved in turn.

Solving equation (1)

Solving for y from

y=0

Solving gives y=0

Solving equation (2)

Solved as second order missing x ode

Time used: 33.930 (sec)

This is missing independent variable second order ode. Solved by reduction of order by using substitution which makes the dependent variable y an independent variable. Using

y=p

Then

y=dpdx=dpdydydx=pdpdy

Hence the ode becomes

yp(y)3(ddyp(y))3+y3p(y)=0

Which is now solved as first order ode for p(y).

Factoring the ode gives these factors

(1)p=0(2)p3p2+y2=0

Now each of the above equations is solved in turn.

Solving equation (1)

Solving for p from

p=0

Solving gives p=0

Solving equation (2)

Let p=p the ode becomes

p3p2+y2=0

Solving for p from the above results in

(1)p=ypp(2)p=ypp

This has the form

(*)p=yf(p)+g(p)

Where f,g are functions of p=p(y). Each of the above ode’s is dAlembert ode which is now solved.

Solving ode 1A

Taking derivative of (*) w.r.t. y gives

p=f+(yf+g)dpdy(2)pf=(yf+g)dpdy

Comparing the form p=yf+g to (1A) shows that

f=1(p)3/2g=0

Hence (2) becomes

(2A)p1(p)3/2=3yp(y)2(p)5/2

The singular solution is found by setting dpdy=0 in the above which gives

p1(p)3/2=0

No valid singular solutions found.

The general solution is found when dpdy0. From eq. (2A). This results in

(3)p(y)=2(p(y)1(p(y))3/2)(p(y))5/23y

This ODE is now solved for p(y). No inversion is needed.

The ode

(1)p(y)=2((p(y))5/2+1)p(y)3y

is separable as it can be written as

p(y)=2((p(y))5/2+1)p(y)3y=f(y)g(p)

Where

f(y)=23yg(p)=((p)5/2+1)p

Integrating gives

1g(p)dp=f(y)dy1((p)5/2+1)pdp=23ydy
2ln(p(y)2(p(y))3/2p(y)p(y)+1)52ln(p(y)+1)5+ln(p(y))=ln(y2/3)+c1

Substituing the above solution for p in (2A) gives

p=y((RootOf(1+(y5e15c12+1)_Z75+(15y5e15c1215)_Z70+(105y5e15c12+105)_Z65+(455y5e15c12455)_Z60+(1365y5e15c12+1365)_Z55+(3000y5e15c123003)_Z50+(4975y5e15c12+5005)_Z45+(6300y5e15c126435)_Z40+(6075y5e15c12+6435)_Z35+(4375y5e15c125005)_Z30+(2250y5e15c12+3003)_Z25+(750y5e15c121365)_Z20+(125y5e15c12+455)_Z15105_Z10+15_Z5)51)2)3/2

Solving ode 2A

Taking derivative of (*) w.r.t. y gives

p=f+(yf+g)dpdy(2)pf=(yf+g)dpdy

Comparing the form p=yf+g to (1A) shows that

f=1(p)3/2g=0

Hence (2) becomes

(2A)p+1(p)3/2=3yp(y)2(p)5/2

The singular solution is found by setting dpdy=0 in the above which gives

p+1(p)3/2=0

Solving the above for p results in

p1=1

Substituting these in (1A) and keeping singular solution that verifies the ode gives

p=y

The general solution is found when dpdy0. From eq. (2A). This results in

(3)p(y)=2(p(y)+1(p(y))3/2)(p(y))5/23y

This ODE is now solved for p(y). No inversion is needed.

The ode

(2)p(y)=2((p(y))5/21)p(y)3y

is separable as it can be written as

p(y)=2((p(y))5/21)p(y)3y=f(y)g(p)

Where

f(y)=23yg(p)=((p)5/21)p

Integrating gives

1g(p)dp=f(y)dy1((p)5/21)pdp=23ydy
2ln(p(y)2+(p(y))3/2p(y)+p(y)+1)5+2ln(p(y)1)5ln(p(y))=ln(1y2/3)+c2

Substituing the above solution for p in (2A) gives

p=y((RootOf((y5e15c22)_Z75+(15y515e15c22)_Z70+(105y5105e15c22)_Z65+(455y5455e15c22)_Z60+(1365y51365e15c22)_Z55+(3000y53003e15c22)_Z50+(4975y55005e15c22)_Z45+(6300y56435e15c22)_Z40+(6075y56435e15c22)_Z35+(4375y55005e15c22)_Z30+(2250y53003e15c22)_Z25+(750y51365e15c22)_Z20+(125y5455e15c22)_Z15105e15c22_Z1015e15c22_Z5e15c22)5+1)2)3/2

For solution (1) found earlier, since p=y then we now have a new first order ode to solve which is

y=0

Since the ode has the form y=f(x), then we only need to integrate f(x).

dy=0dx+c3y=c3

For solution (2) found earlier, since p=y then we now have a new first order ode to solve which is

y=y((RootOf(1+(y5e15c12+1)_Z75+(15y5e15c1215)_Z70+(105y5e15c12+105)_Z65+(455y5e15c12455)_Z60+(1365y5e15c12+1365)_Z55+(3000y5e15c123003)_Z50+(4975y5e15c12+5005)_Z45+(6300y5e15c126435)_Z40+(6075y5e15c12+6435)_Z35+(4375y5e15c125005)_Z30+(2250y5e15c12+3003)_Z25+(750y5e15c121365)_Z20+(125y5e15c12+455)_Z15105_Z10+15_Z5)51)2)3/2

Unable to integrate (or intergal too complicated), and since no initial conditions are given, then the result can be written as

y((RootOf(1+(τ5e15c12+1)_Z75+(15τ5e15c1215)_Z70+(105τ5e15c12+105)_Z65+(455τ5e15c12455)_Z60+(1365τ5e15c12+1365)_Z55+(3000τ5e15c123003)_Z50+(4975τ5e15c12+5005)_Z45+(6300τ5e15c126435)_Z40+(6075τ5e15c12+6435)_Z35+(4375τ5e15c125005)_Z30+(2250τ5e15c12+3003)_Z25+(750τ5e15c121365)_Z20+(125τ5e15c12+455)_Z15105_Z10+15_Z5)51)2)3/2τdτ=x+c4

For solution (3) found earlier, since p=y then we now have a new first order ode to solve which is

y=y

Integrating gives

1ydy=dxln(y)=x+c5

Singular solutions are found by solving

y=0

for y. This is because we had to divide by this in the above step. This gives the following singular solution(s), which also have to satisfy the given ODE.

y=0

For solution (4) found earlier, since p=y then we now have a new first order ode to solve which is

y=y((RootOf((y5e15c22)_Z75(15y515e15c22)_Z70(105y5105e15c22)_Z65(455y5455e15c22)_Z60(1365y51365e15c22)_Z55(3000y53003e15c22)_Z50(4975y55005e15c22)_Z45(6300y56435e15c22)_Z40(6075y56435e15c22)_Z35(4375y55005e15c22)_Z30(2250y53003e15c22)_Z25(750y51365e15c22)_Z20(125y5455e15c22)_Z15+105e15c22_Z10+15e15c22_Z5+e15c22)5+1)2)3/2

Unable to integrate (or intergal too complicated), and since no initial conditions are given, then the result can be written as

y((RootOf((e15c22+τ5)_Z75+(15e15c22+15τ5)_Z70+(105e15c22+105τ5)_Z65+(455e15c22+455τ5)_Z60+(1365e15c22+1365τ5)_Z55+(3003e15c22+3000τ5)_Z50+(5005e15c22+4975τ5)_Z45+(6435e15c22+6300τ5)_Z40+(6435e15c22+6075τ5)_Z35+(5005e15c22+4375τ5)_Z30+(3003e15c22+2250τ5)_Z25+(1365e15c22+750τ5)_Z20+(455e15c22+125τ5)_Z15105e15c22_Z1015e15c22_Z5e15c22)5+1)2)3/2τdτ=x+c6

Will add steps showing solving for IC soon.

Solving for y from the above solution(s) gives (after possible removing of solutions that do not verify)

y((RootOf(1+(τ5e15c12+1)_Z75+(15τ5e15c1215)_Z70+(105τ5e15c12+105)_Z65+(455τ5e15c12455)_Z60+(1365τ5e15c12+1365)_Z55+(3000τ5e15c123003)_Z50+(4975τ5e15c12+5005)_Z45+(6300τ5e15c126435)_Z40+(6075τ5e15c12+6435)_Z35+(4375τ5e15c125005)_Z30+(2250τ5e15c12+3003)_Z25+(750τ5e15c121365)_Z20+(125τ5e15c12+455)_Z15105_Z10+15_Z5)51)2)3/2τdτ=x+c4y((RootOf((e15c22+τ5)_Z75+(15e15c22+15τ5)_Z70+(105e15c22+105τ5)_Z65+(455e15c22+455τ5)_Z60+(1365e15c22+1365τ5)_Z55+(3003e15c22+3000τ5)_Z50+(5005e15c22+4975τ5)_Z45+(6435e15c22+6300τ5)_Z40+(6435e15c22+6075τ5)_Z35+(5005e15c22+4375τ5)_Z30+(3003e15c22+2250τ5)_Z25+(1365e15c22+750τ5)_Z20+(455e15c22+125τ5)_Z15105e15c22_Z1015e15c22_Z5e15c22)5+1)2)3/2τdτ=x+c6y=0y=c3y=exc5

The solution

y((RootOf(1+(τ5e15c12+1)_Z75+(15τ5e15c1215)_Z70+(105τ5e15c12+105)_Z65+(455τ5e15c12455)_Z60+(1365τ5e15c12+1365)_Z55+(3000τ5e15c123003)_Z50+(4975τ5e15c12+5005)_Z45+(6300τ5e15c126435)_Z40+(6075τ5e15c12+6435)_Z35+(4375τ5e15c125005)_Z30+(2250τ5e15c12+3003)_Z25+(750τ5e15c121365)_Z20+(125τ5e15c12+455)_Z15105_Z10+15_Z5)51)2)3/2τdτ=x+c4

was found not to satisfy the ode or the IC. Hence it is removed. The solution

y((RootOf((e15c22+τ5)_Z75+(15e15c22+15τ5)_Z70+(105e15c22+105τ5)_Z65+(455e15c22+455τ5)_Z60+(1365e15c22+1365τ5)_Z55+(3003e15c22+3000τ5)_Z50+(5005e15c22+4975τ5)_Z45+(6435e15c22+6300τ5)_Z40+(6435e15c22+6075τ5)_Z35+(5005e15c22+4375τ5)_Z30+(3003e15c22+2250τ5)_Z25+(1365e15c22+750τ5)_Z20+(455e15c22+125τ5)_Z15105e15c22_Z1015e15c22_Z5e15c22)5+1)2)3/2τdτ=x+c6

was found not to satisfy the ode or the IC. Hence it is removed.

Summary of solutions found

y=0y=c3y=exc5

Maple. Time used: 0.184 (sec). Leaf size: 126
ode:=y(x)*diff(diff(y(x),x),x)^3+y(x)^3*diff(y(x),x) = 0; 
dsolve(ode,y(x), singsol=all);
 
y=0y=c1y=eRootOf(x_Z1_f2(_f)1/3d_f+c1)dx+c2y=eRootOf(x+2(_Z1i(_f)1/33+2_f2+(_f)1/3d_f)+c1)dx+c2y=eRootOf(x2(_Z1i(_f)1/332_f2(_f)1/3d_f)+c1)dx+c2

Maple trace

`Methods for second order ODEs: 
   *** Sublevel 2 *** 
   Methods for second order ODEs: 
   Successful isolation of d^2y/dx^2: 3 solutions were found. Trying to solve each resulting ODE. 
      *** Sublevel 3 *** 
      Methods for second order ODEs: 
      --- Trying classification methods --- 
      trying 2nd order Liouville 
      trying 2nd order WeierstrassP 
      trying 2nd order JacobiSN 
      differential order: 2; trying a linearization to 3rd order 
      trying 2nd order ODE linearizable_by_differentiation 
      trying 2nd order, 2 integrating factors of the form mu(x,y) 
      trying differential order: 2; missing variables 
      `, `-> Computing symmetries using: way = 3 
      Try integration with the canonical coordinates of the symmetry [0, y] 
      -> Calling odsolve with the ODE`, diff(_b(_a), _a) = -_b(_a)^2+(-_b(_a))^(1/3), _b(_a), explicit, HINT = [[1, 0]]`         *** 
         symmetry methods on request 
      `, `1st order, trying reduction of order with given symmetries:`[1, 0]
 

Mathematica. Time used: 2.742 (sec). Leaf size: 800
ode=y[x]*D[y[x],{x,2}]^3+y[x]^3*D[y[x],x]==0; 
ic={}; 
DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
 
Solution too large to show

Sympy. Time used: 0.253 (sec). Leaf size: 3
from sympy import * 
x = symbols("x") 
y = Function("y") 
ode = Eq(y(x)**3*Derivative(y(x), x) + y(x)*Derivative(y(x), (x, 2))**3,0) 
ics = {} 
dsolve(ode,func=y(x),ics=ics)
 
y(x)=0