3. Find the error that was made in solving the problem below. Identify the error and explain what was performed incorrectly. Problem Statement: Determine the open intervals in which the function f(x) = x* 2x -8 is increasing or decreasing. 4. Find the points of inflection and discuss the concavity of the graph of the function f(x) = x3 - 6x2 + 12x.5. Acompany has determined that its total revenue (in dollars) can be modeled by R = 400x x? where x is the number of units produced (and sold). (a) What number of units will maximize revenue? (b) What is the maximum revenue