How do I find the singular solution of the differential equation y' = (y^2 + 1)/(xy + y)?

klesstilne1

klesstilne1

Answered question

2022-11-17

How do I find the singular solution of the differential equation y = y 2 + 1 x y + y ?
I start out with the separable differential equation,
y = d y d x = y 2 + 1 x y + y = y 2 + 1 y ( x + 1 )
Thus, 1 x + 1 d x = y y 2 + 1 d y
Then integrating both sides of the equation, I get
ln ( x + 1 ) = 1 2 ln ( y 2 + 1 ) + C
Now, e ln ( x + 1 ) = e 1 2 ln ( y 2 + 1 ) + C . So...
( x + 1 ) = e C ( y 2 + 1 ) 1 2
I kind of wanted to know if this is indeed the correct general formula. And also, how would I find the singular solution, if there happens to be one in this case.

Answer & Explanation

Eva Cochran

Eva Cochran

Beginner2022-11-18Added 14 answers

MathJax(?): Can't find handler for document MathJax(?): Can't find handler for document For an arithmetic sequence the nth term is found by using the nth term formula.
Reminder | 2 2 a n = a 1 + ( n - 1 ) d 2 2 | ̲ ¯
a 13 = - 5 + ( 12 × 7 )
a 13 = - 5 + 84
a 13 = 79
drogaid1d8

drogaid1d8

Beginner2022-11-19Added 1 answers

You correctly obtained the general solution :
(1) x + 1 = C 1 y 2 + 1
Writing it on explicit form for y ( x ):
(2) y ( x ) = ± C 2 ( x + 1 ) 2 1
with C 2 = 1 C 1 2
The result presented on the form (2) forgets the particular case C 1 = 0 which corresponds to the singular solution x = 1, any y, that is x ( y ) = 1 , which is represented by a vertical straight line in Cartesian coordinates.
The line x ( y ) = 1 is the envelope of the curves of Eq. ( 2 )

Do you have a similar question?

Recalculate according to your conditions!

New Questions in Differential Equations

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?