# Bernoulli Differential Equation?

1. Mar 2, 2010

### jofree87

I keep getting stuck on one part of the equation. can somebody help?

dy/dx = y(xy3 - 1)

dy/dx = xy4 - y

dy/dx + y = xy4

u = y1-n = y-3

y = u-3

dy/dx = dy/du * du/dx

dy/dx = -3u-4 du/dx

Substituting terms into the original equation

-3u-4 du/dx + u-3 = x(u-3)4

Here is where I get stuck. When I divide u-4 to clean up the equation, the right hand side still has u-8 remaining. I will not be able to go on since the right hand side can only have x terms. What am I doing wrong?

Last edited: Mar 2, 2010
2. Mar 2, 2010

Hi jofree87!
erm … noooo!