# Thread: Extreme Value Problems

1. ## Extreme Value Problems

A box with an open top is to be constructed from a square piece of cardboard, 6 meters wide, by cutting out a square from each of the four corners, and bending up the sides. Find the largest volume that such a box can have.

Let x represent the dimensions

$V = (6 - 2x)^2x$
$V = 36x - 24x^2 + 4x^{3}$

$V' = 36 - 48x + 12x^2$
$0 = 36 - 48x + 12x^2$
$0 = 12(x - 1)(x - 3)$

$x = 1 and x = 3$

Restrictions: $0 \leq x \leq 3$

$V = Lwh$
$V = (3)(1)(6)$
$V = 18m^{3}$

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Text Answer is $16m^{3}$

2. Originally Posted by Macleef
A box with an open top is to be constructed from a square piece of cardboard, 6 meters wide, by cutting out a square from each of the four corners, and bending up the sides. Find the largest volume that such a box can have.

Let x represent the dimensions

$V = (6 - 2x)^2x$
$V = 36x - 24x^2 + 4x^{3}$

$V' = 36 - 48x + 12x^2$
$0 = 36 - 48x + 12x^2$
$0 = 12(x - 1)(x - 3)$

$x = 1 and x = 3$

Restrictions: $0 \leq x \leq 3$

$V = Lwh$
$V = (3)(1)(6)$
$V = 18m^{3}$

---------

Text Answer is $16m^{3}$

$V(x) = (6 - 2x)^2x$
$V(1) = (6 - 2(1))^2(1)=(4)^2=16$