A company is constructing an open-top, square-based, rectangular metal tank that will have a volume of 64 ft3. what dimensions yield the minimum surface area? round to the nearest tenth, if necessary.

Answer :

carlosego

To solve this problem you must apply the proccedure shown below:

1. You must use the formula for calculate the surface area and the volume of the tank:

[tex] 1) SA=x^{2} +4xy\\ 2) V=x^{2} y\\ 64=x^{2} y [/tex]

2. Solve for [tex] y [/tex] in the second equation and substitute it into the first one.Then, you have:

[tex] y=\frac{64}{x^{2}} \\ SA=x^{2} +4x(\frac{64}{x^{2}}) [/tex]

3. Now, derivate:

[tex] SA'=2x-256x^{-2} \\ 2x-256x^{-2}=0
[/tex]

4. When you solve for [tex] x [/tex], you obtain:

[tex] 2x^{3}-256=0\\ x=\sqrt[3]{\frac{256}{2}} \\ x=5.03 [/tex]

5. Now, you must calculate [tex] y [/tex]:

[tex] y=\frac{64}{(5.03)^{2}} \\ y=2.52 [/tex]

Therefore, the dimensions are:

The sides of the base of the tank: [tex] 5.03 feet [/tex]

The height of the tank: [tex] 2.52 feet [/tex]

aksnkj

Answer:

The sides of the base of the tank: 5.03 feet

The height of the tank: 2.52 feet

Step-by-step explanation:

Given:

Volume of an open-top, square-based, rectangular metal tank = 64 [tex]ft^{3}[/tex]

Let:

The side of the square base  = x ft

Height of the tank = y

So, The volume of the tank = [tex]x^{2} y[/tex]

                                         [tex]64=x^{2} y[/tex]     ........(i)

And surface area = [tex]x^{2} +4xy[/tex]

From (i)

                  Surface area (SA)= [tex]x^{2} +4x(\frac{64}{x^{2} } )[/tex]

Now, Differentiate

                  (SA)' = [tex]2x-256x^{-2}[/tex]

                   [tex]0=2x-256x^{-2}[/tex]

solve for , you obtain:

                  [tex]2x^{3} -256=0\\x=\sqrt[3]{\frac{256}{2} } \\x=5.03[/tex]

Now, you must calculate

                  [tex]y=\frac{64}{x^{2} } \\y=\frac{64}{5.03^{2} } \\y=2.52[/tex]

Therefore, the dimensions are:

The sides of the base of the tank: 5.03 feet

The height of the tank: 2.52 feet

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