Answer:
a) h = 123/x^2
b) S = x^2 +492/x
c) x ≈ 6.27
d) S'' = 6; area is a minimum (Y)
e) Amin ≈ 117.78 m²
Step-by-step explanation:
a) The volume is given by ...
V = Bh
where B is the area of the base, x^2, and h is the height. Filling in the given volume, and solving for the height, we get:
123 = x^2·h
h = 123/x^2
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b) The surface area is the sum of the area of the base (x^2) and the lateral area, which is the product of the height and the perimeter of the base.

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c) The derivative of the area with respect to x is ...

When this is zero, area is at an extreme.
![0=2x -\dfrac{492}{x^2}\\\\0=x^3-246\\\\x=\sqrt[3]{246}\approx 6.26583](https://tex.z-dn.net/?f=0%3D2x%20-%5Cdfrac%7B492%7D%7Bx%5E2%7D%5C%5C%5C%5C0%3Dx%5E3-246%5C%5C%5C%5Cx%3D%5Csqrt%5B3%5D%7B246%7D%5Capprox%206.26583)
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d) The second derivative is ...

This is positive, so the value of x found represents a minimum of the area function.
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e) The minimum area is ...

The minimum area of metal used is about 117.78 m².
Answer:
abt 8.77
Step-by-step explanation:
In the question it is already given that Eric drove for 439.92 miles on 15.6 gallons. It is required to find the distance traveled on 39.7 gallons of gas. Also we have to find the answer to the nearest hundredth.
Then,
In 15.6 gallons Eric can drive for a distance = 439.92 miles
In 39.7 gallons Eric can drive for a distance = [(439.92/15.6) * 39.7] miles
= 1119.54 miles
So the total distance traveled by Eric is 1120 miles with 39.7 gallons of gas. The answer has been calculated to the nearest hundredth.
We are trying to find miles/hour, which shows that we are going to be dividing the total number of miles by the total number of hours. Thus, in this case, the miles/hour rate will be:

He drove 40 miles in one hour.