(a) (b) {c} A company finds that its revenue R in thousands of dollars is given by the function R(x) = 40.x x2, where x is the number of products sold in thousands. Determine the numberof products that should be sold to maximize the revenue. A stone is thrown vertically upward with an initial velocity of 20 mls. Neglecting air resistance, determine the time at which the stone reaches its maximum height and the maximum height itself. A llimeter ladder is leaning against a wall. The bottom of the ladder is sliding away from the wall at a rate of 0.5 meters per second. How fast is the top of the ladder sliding down the wall when the bottom is 6 meters away from the wall