What do youmeanby "simply integrate dy/dx"? And with respect to what variable? I imagine you started with .

Youcouldwrite this as . It is, of course easy to integrate on left to get just "y". But how are you going to integrate on the right? This is NOT a partial derivatives problem so you cannot just treat "y" like a constant- it is an unknown function of x so you cannot integrate it with respect to x.