Question

How do you find dy/dx for `y + 2x - 3xy^3 = 4`?

Answer 1

You must remember that `y` is a function of `x` so that to take into account this you have to include `(dy)/(dx)` when deriving any `y` in your function, as:
`1(dy)/(dx)+2-3y^3-9xy^2(dy)/(dx)=0`
Collecting `(dy)/(dx)`:
`(dy)/(dx)=(3y^3-2)/(1-9xy^2)`