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Since the tutor @ankor@dixie-net.com made several mistakes in his solution, I re-write and edit it in correct way.
The container does not have a top.
The base and sides are rectangular.
The width is x cm. The length is 4 times the width.
The volume is 600 cm^3.
Determine the minimum surface area to two decimal places.
:
let h = the height of the box
Given
x = the width
4x = the length
Volume
4x * x * h = 600
4x^2 * h = 600
h =
cancel the 4
h = <<<---=== I replaced 120 by 150
:
Surface area
S.A. =(4x*x) + 2(4x*h) + 2(x*h)
S.A. = 4x^2 + 8xh + 2xh
S.A. = 4x^2 + 10xh
replace h with
S.A. = 4x^2 + 10x*
Cancel x
S.A. = 4x^2 +
plot the equation y = 4x^2 + (1500/x), where y = the surface area
Taking the derivative y' = 8x - 1500/x^2 = , <<<---=== I re-wrote this part
you will find the minimum surface area occurs when x = = 5.72
Find the minimum surface area
S.A. =
Answer S.A. = 393.1 cm^2.