A cylindrical can is to hold 20 m3. The material for the top and bottom costs(adsbygoogle = window.adsbygoogle || []).push({});

€10/m^2 and material for the side costs €8/m^2. Find the radius r and height h of

the most economical can.

the answer is h= 5 and j=2

i have found the eqn such as v=pi j^2 h =20 pi

and 2pi j^2 + pi j h = 18...then i don't know how to do.....pls help

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# Extrema physics problem

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