1. Find the change in surface area dA (in units2) if the radius of a sphere changes from r by dr.
2. Find the change in volume dV (in units3) if the sides of a cube change from 9 to 9.1.
3. Find the change in volume dV (in cm3) if a circular cylinder with r = 4 cm changes height from 3 cm to 3.05 cm.