dx 9. If y =. X 1+x3 find when = 4 and x = 2. dt dt In 10-14, Include the correct units in your answer! 10. A sphere's volume is increasing at 5 cm /sec. Find the rate of change of the radius when r = 1.25 cm. 11. A blue car is approaching an intersection from the south at 25 mph and a red car is leaving the same intersection going east at 35 mph. When the blue car is 1.5 miles from the intersection and the red car is 2 miles from the intersection, at what rate is the distance between the cars changing? 12. A 26-ft ladder is leaning against a wall and the ladder's base is being pushed along the ground toward the wall at a rate of 0.8 inches per second. When the ladder hits the wall 24 feet above the ground, a) at what rate is the ladder climbing the wall? b) at what rate is the angle between the ladder and the ground changing? 13. An inverted cone is being filled with oil at a rate of 52n cubic cm per minute. The cone is 80 cm deep and 80 cm wide at its top. What is the rate at which the depth is changing when the depth is 16 cm? V 14. A pebble was dropped into a lake and created circular ripples. The area of those circles increased at a rate of 3 cm /sec. Find the rate of change of the radius when the radius was 2.5 cm