Model the total stopping distance by the equation y = x2 / 20 + x, where 20 x represents the speed in miles per hour and y represents the total stopping distance in feet.
a. Graph this equation for the values of x, where x ≤ 70 mi/h.
b. Use the graph to approximate the stopping distance for a car traveling at 53mi/h.
c. Use the graph to approximate the speed for a car that stops completely after 70 feet.