the surface area of a cylinder is increasing by 2 pi square inches per hour and the height is decreasing by 0.1 inches per hour when the radius is 16 inches and the height is 7 inches. how fast is the radius of the cylinder changing?
The decreasing part area :0.1×2×Pi×r ＝0.2 Pi r The increasing part is 2 pi square. the top and bottom area now: 2pi ×(16＋X) X means the increasing inches. Then use the top and bottom part miners the decreasing equals to the the increasing part. Then the answer you can calculate by yourself....
