Initial value problem, end of problem Q

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Homework Help Overview

The discussion revolves around solving an initial value problem (I.V.P.) involving a differential equation represented as x²(dy/dx) = (4x² - x - 2)/((x + 1)(y + 1)), with the condition y(1) = 1. Participants are exploring the implications of the quadratic form of the equation derived from their attempts at a solution.

Discussion Character

  • Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the transformation of the equation into a quadratic form and the challenges associated with it. Questions arise regarding the feasibility of solving for y and the methods to approach the quadratic equation, including the quadratic formula and completing the square.

Discussion Status

There is ongoing exploration of different methods to solve the quadratic equation for y. Some participants suggest using the quadratic formula, while others consider completing the square, indicating a productive exchange of ideas without a clear consensus on the best approach.

Contextual Notes

Participants express confusion regarding the variables involved and the complexity of the quadratic equation derived from the original differential equation. There is an acknowledgment of the initial conditions and their role in determining constants within the equation.

csc2iffy
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Homework Statement


Solve the I.V.P. x2(dy/dx) = (4x2-x-2)/((x+1)(y+1)) , y(1)=1


Homework Equations





The Attempt at a Solution


So far, I got to this:
y2/2 + y = log(x) + 2/x + 3log(x+1) + C
I used the initial conditions to solve for C and got:
C = -1/2 - 3log(2)
Substituting C back in:
y2/2 + y = log(x) + 2/x + 3log(x+1) + (-1/2 - 3log(2))
Now my question is, is it possible to solve for y or is this as far as I can go with the problem?
 
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csc2iffy said:
y2/2 + y = log(x) + 2/x + 3log(x+1) + (-1/2 - 3log(2))
Now my question is, is it possible to solve for y or is this as far as I can go with the problem?

Well it is a quadratic, not the nicest one but you can solve it for y.
 
How do I set it up as a quadratic? I'm getting a little lost with all of the variables
 
csc2iffy said:
How do I set it up as a quadratic? I'm getting a little lost with all of the variables

[tex]y^2 + 2y -2[\frac{2}{x} + \ln(x(x+1)^3)] = 0[/tex]

[tex]\text{Then quadratic formula } y = \frac{-2\pm\sqrt{4 - 4(1)(-2[\frac{2}{x} + \ln(x(x+1)^3)])}}{2(1)}[/tex]

It's horrible, but it'll give you values of y.
 
Last edited:
could i just complete the square to get:
y = +/- √[2(log(x) + (2/x) + 3log(x+1) + C) + 1] - 1
?
 
Bread18 said:
[tex]y^2 + 2y -2[\frac{2}{x} + \ln(x(x+1)^3)] = 0[/tex]

[tex]\text{Then quadratic formula } y = \frac{-2\pm\sqrt{4 - 4(1)(-2[\frac{2}{x} + \ln(x(x+1)^3)])}}{2(1)}[/tex]

It's horrible, but it'll give you values of y.

Oops forgot the + C, but you get the idea.

csc2iffy said:
could i just complete the square to get:
y = +/- √[2(log(x) + (2/x) + 3log(x+1) + C) + 1] - 1
?

Completing the square would probably be a lot harder, but it should work.
 

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