# Thread: [SOLVED] Express the surface area as a function

1. ## [SOLVED] Express the surface area as a function

A rectangular box has a square base and a volume of 80 cubic inches. If the side of the base has length x and the height of the box is h, express the surface area of the box as a function of x.

2. Originally Posted by moonman
A rectangular box has a square base and a volume of 80 cubic inches. If the side of the base has length x and the height of the box is h, express the surface area of the box as a function of x.
Since the box has a square base, so, length = x and width = x, height = h.

$
volume = x.x.h = 80
$

$
x^2h = 80
$

$
h = \frac{80}{x^2}
$

Now,

$surface \;\;area = 2(x.x + x.h + x.h)$

$= 2(x^2 + 2xh)$

$= 2x^2+4xh$

$= 2x^2+4x\left(\frac{80}{x^2}\right)$

$= 2x^2+\frac{320}{x}$

Did you get it now ???

3. Originally Posted by Shyam
Did you get it now ???
You couldn't have made it easier

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