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One formula stating the relationship between the length L and width w of a rectangle
of “pleasing proportion” is L^2 = w(L + w). How should a 4 feet by 8 feet sheet
of plasterboard be cut so that the result is a rectangle of “pleasing proportion” with a width of 4 feet?
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Let's take w= 4 feet and find L from this equation
L^2 = w*(L + w).
So,
L^2 = 4*(L + 4)
L^2 - 4L - 16 = 0
= = = .
We disregard the negative root and accept the positive one L = = 6.472135955.
So, the cut should be at L = 6.472 feet from the 4 ft edge. ANSWER
Solved.
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By the way, this problem was solved at this forum many years ago (~ 15 years ago) under this link
https://www.algebra.com/algebra/homework/quadratic/Quadratic_Equations.faq.question.669064.html