Question

Help

Answer 1

At 3:07 and onward what is he doing?

https://www.youtube.com/watch?v=Mg4s5lGQ0UQ

Re-learning diff eq.

Answer 2

@IrishBoy123

Answer 3

he's stating the obvious, i think

you are looking at the Integrating Factor approach, the first resort after an ODE is non-separable.

but the position on the LHS of the equation is usually taken as obvious because you have reached a certain level.

he's spelling it out by re-stating the Product Rule.

Answer 4

Oh... Yes, I see now.