does anyone know which of these are differential equations

Question

1) x dx/dy -y = 2x^2
2) dy/dx + x^3y = sin y
3) 1/y dy/dx + y cosx = 3x

thanks

Answer 1

I guess they all are, though usually, we write dy/dx if y is a function of x.
In that case, you'd have

x / (dy/dx) - y = 2x^2

which does not qualify, since dy/dx is in the denominator.