Answer:
[tex]W = 8.255[/tex]
[tex]L = 31.02[/tex]
Step-by-step explanation:
Let L = Length and W = Width.
So:
[tex]L = 4W - 2[/tex]
[tex]Area = 256[/tex]
Required
Find L and W
Area is calculated as:
[tex]Area = L * W[/tex]
Substitute 4W - 2 for L and 256 for Area
[tex]Area = (4W - 2) * W[/tex]
[tex]256 = (4W - 2) * W[/tex]
Open Bracket
[tex]256 = 4W^2 - 2W[/tex]
Divide through by 2
[tex]128 = 2W^2 - W[/tex]
Equate to 0
[tex]2W^2 - W - 128 = 0[/tex]
An equation [tex]aw^2 + bw + c = 0[/tex] has the roots
[tex]W = \frac{-b\±\sqrt{b^2 - 4ac}}{2a}[/tex]
Where
[tex]a = 2[/tex] [tex]b = -1[/tex] [tex]c = -128[/tex]
So:
[tex]W = \frac{-(-1)\±\sqrt{(-1)^2 - 4*2*-128}}{2*2}[/tex]
[tex]W = \frac{1\±\sqrt{1 +1024}}{4}[/tex]
[tex]W = \frac{1\±\sqrt{1025}}{4}[/tex]
[tex]W = \frac{1\± 32.02}{4}[/tex]
[tex]W = \frac{1+ 32.02}{4}[/tex] or [tex]W = \frac{1 - 32.02}{4}[/tex]
[tex]W = \frac{33.02}{4}[/tex] or [tex]W = \frac{-31.02}{4}[/tex]
[tex]W = 8.255[/tex] or [tex]W = -7.755[/tex]
But the dimension can not be negative.
So:
[tex]W = 8.255[/tex]
Recall:
[tex]L = 4W - 2[/tex]
[tex]L = 4 * 8.255 - 2[/tex]
[tex]L = 31.02[/tex]
