1) if y = x3 + 2x and dx/ dt = 5, find dy/dt when x = 2. give only the numerical answer. for example, if dy, dt = 3, type only 3.

2)the area a = πr2 of a circular puddle changes with the radius. at what rate does the area change with respect to the radius when r = 5ft?

5π ft2/ft
5 ft2/ft
10π ft2/ft
25π ft2/ft

3)a 25-ft ladder rests against a vertical wall. if the bottom of the ladder slides away from the wall at a rate of 0.18 ft/sec, how fast, in ft/sec, is the top of the ladder sliding down the wall, at the instant when the bottom of the ladder is 20 ft from the wall? answer with 2 decimal places. type your answer in the space below. if your answer is a number less than 1, place a leading "0" before the decimal point (ex: 0.35).