I'm trying to understand what is wrong with this solution, since I'm not getting the same answer in

dikcijom2k

dikcijom2k

Answered question

2022-07-02

I'm trying to understand what is wrong with this solution, since I'm not getting the same answer in Matlab
y x y = x y 3 / 2 , y ( 1 ) = 4
y x y = x y 3 / 2 d y d x = x ( y + y 3 / 2 ) d y ( y + y 3 / 2 ) = x d x 2 ln 1 + y y = x 2 2 + c y = 1 ( 1 e x 2 4 + c ) 2 4 = 1 ( 1 e 1 4 + c ) 2 c = 0.655 y = 1 ( 1 e x 2 4 0.655 ) 2
This is what I'm getting in Matlab
( ( tanh ( x 2 8 + atanh ( 3 ) 1 8 ) + 1 ) 2 4 ( tanh ( x 2 8 + atanh ( 5 ) + 1 8 ) 1 ) 2 4 )

Answer & Explanation

Nathen Austin

Nathen Austin

Beginner2022-07-03Added 14 answers

I think
y = 1 ( 1 e x 2 4 + c ) 2
instead of what you wrote. y cannot be negative anyway, as y is present in the equations.
cooloicons62

cooloicons62

Beginner2022-07-04Added 4 answers

If you distribute the constant in the exponent to be also a factor, then you get to
1 + y 1 / 2 = C e 1 x 2 4
and from that to C = 3 2 , so that in the end
y ( x ) = ( 3 2 e 1 x 2 4 1 ) 2
One can now express the exponential in various ways in terms of hyperbolic functions, for instance one has that coth ( u ) + 1 = e u sinh ( u ) = 2 1 e 2 u , which has a resemblance to parts of the solution.

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?