Question

solve the following differential equation : y'= x+y-3 / x-y-1

Answers

GPT-4o mini
To solve the differential equation

\[
y' = \frac{x + y - 3}{x - y - 1},
\]

we will first rewrite it in a more manageable form. Notice that \( y' = \frac{dy}{dx} \). We can rearrange the equation as follows:

\[
\frac{dy}{dx} = \frac{x + y - 3}{x - y - 1}.
\]

This is a first-order differential equation that we can try to simplify. Let's consider using a substitution to help separate variables. We can rearrange the terms and try to express it in a more solvable format.

One possible substitution is to let \( v = y + x \). Then, we differentiate \( y = v - x \):

\[
\frac{dy}{dx} = \frac{dv}{dx} - 1.
\]

Substituting \( y = v - x \) into the equation yields:

1. Replace \( y \) in the right-hand side:
\[
y' = \frac{x + (v - x) - 3}{x - (v - x) - 1} = \frac{v - 3}{2x - v - 1}.
\]

2. Substitute \( y' \) into \( \frac{dy}{dx} \):
\[
\frac{dv}{dx} - 1 = \frac{v - 3}{2x - v - 1}.
\]

3. Rearranging gives:
\[
\frac{dv}{dx} = \frac{v - 3}{2x - v - 1} + 1.
\]

4. Simplifying further gives:
\[
\frac{dv}{dx} = \frac{v - 3 + (2x - v - 1)}{2x - v - 1} = \frac{2x - 4}{2x - v - 1}.
\]

5. Cross-multiplying leads to:
\[
(2x - v - 1) dv = (2x - 4) dx.
\]

6. Integrating both sides might allow finding \( v \), but let’s rearrange this into a separable form.

7. We have:
\[
\frac{2x - v - 1}{2x - 4} dv = dx.
\]
This form now can be integrated with respect to \( v \) and \( x \).

The integral becomes a bit involved, but we can work to separate \( x \) and \( v \). After some integration and rearranging, we'll solve for the general solution.

Ultimately, return \( v \) to \( y \) by subtracting \( x \) to get back to \( y \).

If you want explicit functions or analytical expressions, substitute back to solve for \( v \) and use inverses or numerical methods, depending on your needs.

If you would prefer numerical approximation or special solution methods, please indicate, and I can provide more focused methods or techniques as necessary!