(a) A company makes computer chips from square wafers of silicon. It wants to keep the side length of a wafer very close to 15 mm, and it wants to know how the area of a wafer changes when the side length changes.
Find . [Can you explain its meaning in this situation?]

(b) What is the rate of change of the area of the square with respect to its side length when the perimeter is mm?

(a) sq mm/ mm
(b) sq mm/mm

You can earn partial credit on this problem.