At what point would you use surface area, rather than just area?
You would use surface area when coming in contact with a 3D object that you want to know the entire area of vs. just one surface on said 3D object or different 2D object.
Which operation would you use to find the area underneath the curve from point A to point B?
In order to find the area underneath the curve, you would need to find the integral of the equation from point A to point B.
At which point does a monopolist set their prices in order to maximize profits?
A monopolist sets their prices at the point at which Marginal revenue equals marginal cost.