Question 51237:  John has 300 feet of lumber to frame a rectangular patio (the perimeter of a rectangle is 2 times length plus 2 times width). He wants to maximize the area of his patio (area of a rectangle is length times width). What should the dimensions of the patio be, and show how the maximum area of the patio is calculated from the algebraic equation.   
 Answer by venugopalramana(3286)      (Show Source): 
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Amanda has 400 feet of lumber to frame a 
rectangular patio (the perimeter of a rectangle is 2 
times length plus 2 times width). She wants to 
maximize the area of her patio (area of a rectangle is 
length times width). What should the dimensions of the 
patio be, and show how the maximum area of the patio 
is calculated from the algebraic equation. 
Answer: 
IF L AND B ARE DIMENSIONS WE HAVE 
PERIMETER=2(L+B)=400.....OR.....L+B=200..OR......B=200-L.................I 
AREA=A 
=LB=L(200-L)=200L-L^2=-{L^2-200L}=-{(L^2)-2(L)(100)+100^2-100^2} 
A=10000-(L-100)^2 
(L-100)^2 BEING PERFECT SQUARE,ITS MINIMUM VALUE IS 
ZERO. 
HENCE AREA IS MAXIMUM WHEN L-100 IS ZERO,OR WHEN L=100 
AND THEN THE MAXIMUM AREA WOULD BE 
A-MAX.=10000-0=10000 
DIMENSIONS ARE 100*100 
 
 
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