The area of the paper is of 24 square
inches.
A = x*y
24 = x*y
=> y = 24/x
The dimensions of the rectangular layout
are:
A(x) = (x+2)(y+3)
A(x) =
(x+2)(24/x + 3)
To determine the dimensions that will
minimize the amount of paper, we'll have to calcualte the 1st derivative of the area
function.
We'll use the product
rule:
A'(x) = (x+2)'*(24/x + 3) + (x+2)*(24/x +
3)'
A'(x) = 24/x + 3-
24(x+2)/x^2
A'(x) = (24x + 3x^2 - 24x -
48)/x^2
We'll eliminate like
terms:
A'(x) = ( 3x^2 -
48)/x^2
We'll cancel
A'(x);
A'(x) = 0
( 3x^2 -
48)/x^2 = 0 => 3x^2 - 48 = 0 => 3x^2 = 48 => x^2 = 16 => x1
= 4, x2 = -4
Since a dimension cannot be negative, we'll
reject the negative value -4.
y = 24/4 => y =
6
Therefore, the minim dimensions of the
paper are: x = 4 and y = 6.
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