Friday

August 29, 2014

August 29, 2014

Posted by **sh** on Wednesday, December 8, 2010 at 9:45pm.

V=πr²h=32pi SA=2πr²+2πrh

h=32/r²

Domain={r>o}

Let x be the cost, I subbed 32/r² for h

C=f(r)=2πxr²+(32xπ/r)

f'(r)=4πxr + 32xπ/r²

common denominator

f'(r)=(4πxr³+ 32xπ)/r²

I factored, it, r=-2, which is not in the domain.

Where did it go wrong?

- Calculus -
**Reiny**, Wednesday, December 8, 2010 at 10:58pmCost = 2(2πr^2) + 1(2πrh)

= 4πr^2 + 2πr(32/r^2)

= 4πr^2 + 64π/r

d(Cost)/dr = 8πr - 64π/r^2 = 0 for a min of Cost

8πr = 64π/r^2

r^3 = 8

r = 2

h = 32/4 = 8

Can should have a radius of 2 and a height of 8

- Calculus -
**sh**, Wednesday, December 8, 2010 at 11:13pmI did the derivative wrong! Thanks!

**Related Questions**

Calculus - dimensions of a box? - A rectangular box with a square bottom and a ...

math-optimal diameterand height - A cylindrical oil-storage tank is to be ...

Math - Ignoring the walls’ thickness, determine the outside dimensions that will...

Math - Ignoring the walls’ thickness, determine the outside dimensions that will...

the lagrange multiplier equation - A cylindrical oil-storage tank is to be ...

Calculus - A company is designing shipping crates and wants the volume of each ...

lagrange multipliers - A cylindrical oil-storage tank is to be constructed for ...

calculus - An open box is to be constructed so that the length of the base is 4 ...

Calculus,math - Constuct a rectangular box with a square base that holds a given...

Calculus - A box is constructed out of two different types of metal. The metal ...