Hello, Tactified!

I'll give you a complete walk-through . . . with baby-steps.

A closed rectangular box with a square base is to have a volume of 2000 cm³.

It costs twice as much per cm² for the top and bottom as it does for the sides.

Find the dimensions of the container of least cost. Code:

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The volume of the box is 2000 cm³: . .[1]

The four sides of the box have an area of cm² each: .

Let = price of material per cm² for the sides.

. . dollars.

The ends (top and bottom) of the box have an area of cm² each: .

The ends cost per cm².

. . dollars.

Hence, the total cost is: . .[2]

Substitute [1] into [2]: .

Therefore, we must minimize: .

Got it?

Awww, too slow again . . . *sigh*

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