A cylinder can is to have a volume of 900 cm cubed. The metal costs $15.50/squared meter. What dimensions produce a can with minimum cost? What is the cost of making the can?

Question

anonymous · Answer

attachment

anonymous · Answer

Am I doing it right?

e.mccormick · Answer

I see an issue with your derivative.

anonymous · Answer

please point it out

e.mccormick · Answer

$\cfrac{27900}{r}=27900r^{-1}$ Use this second form of it and the exponent rules you know and see what you get.

anonymous · Answer

i get |dw:1371523952498:dw|

e.mccormick · Answer

Yes.  Your other part, the $+62\pi r$ is fine, so now add those fractions up and see where you go.

e.mccormick · Answer

Your mistake was in how you took the derivative of that.  Other than that, the next steps looked pretty good, but got fowled up by involving the wrong C'.

anonymous · Answer

Was the c' was wrong due to my wrong derivative?

e.mccormick · Answer

Yes.

e.mccormick · Answer

You come up with a new, reduced equation?  In your first one, you elimitated the $r^2$ on the bottom.  In this, there is a little more you can cancel out.  The 62.

anonymous · Answer

|dw:1371526270946:dw|