In a rectangle, the length is increasing at a rate of 0.4 cm/s while the width is decreasing at a rate of 0.3 cm/s. At what rate is the area of the rectangle changing when the length is 50 cm and the width is 30 cm? Is the area increasing or decreasing at that time? Find all the values of c guaranteed by the Mean Value Theorem for f(x) = 13-412 on [0, 2]