SOLUTION: The surface area of a right circular cylinder of height 4 feet and radius r feet is given by S(r)=2πrh+2πr2. Find the instantaneous rate of change of the surface area wit

Algebra ->  Finance -> SOLUTION: The surface area of a right circular cylinder of height 4 feet and radius r feet is given by S(r)=2πrh+2πr2. Find the instantaneous rate of change of the surface area wit      Log On


   

Question 1102748: The surface area of a right circular cylinder of height 4 feet and radius r feet is given by S(r)=2πrh+2πr2. Find the instantaneous rate of change of the surface area with respect to the radius, r, when r = 4.
A) 24π
B) 16π
C) 64π
D) 20π
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Take the derivative of the surface area function with respect to r,
dS%2Fdr=2pi%2Ah%2B4pi%2Ar
dS%2Fdr=2pi%28h%2B2r%29
So when r=4,
dS%2Fdr=2pi%284%2B2%284%29%29
Work that out for the solution.