Post

Created by @nathanedwards
 at November 30th 2023, 8:11:16 pm.

Question: Suppose a function f(x,y) f(x, y) can be expressed as the product of two functions, g(x) g(x) and h(y) h(y) . Use separation of variables to solve the following differential equation:

y=x2y1 y' = \frac{x^2}{y-1}

Answer: We are given the differential equation y=x2y1 y' = \frac{x^2}{y-1} and we want to solve it using separation of variables.

First, we express f(x,y) f(x, y) as the product of two functions:

f(x,y)=g(x)h(y) f(x, y) = g(x) \cdot h(y)

We can rewrite the differential equation as follows:

y=x2y1 y' = \frac{x^2}{y-1}
y(y1)=x2 y' \cdot (y-1) = x^2

Now, we proceed with separating the variables:

(y1)dydx=x2 (y-1) \cdot \frac{dy}{dx} = x^2

We can now integrate both sides with respect to their respective variables:

(y1)dy=x2dx \int (y-1) \cdot dy = \int x^2 \cdot dx
12y2y=13x3+C \frac{1}{2}y^2 - y = \frac{1}{3}x^3 + C

Here, C C is the constant of integration.

So, the general solution is given by:

12y2y=13x3+C \frac{1}{2}y^2 - y = \frac{1}{3}x^3 + C

This is our solution using separation of variables.