SOLUTION: The length of a rectangle is 4 less than twice its width. If the area of the rectangle is 20, the width of the rectangle to the nearest tenth is

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Question 284970: The length of a rectangle is 4 less than twice its width. If the area of the rectangle is 20, the width of the rectangle to the nearest tenth is
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
L=2W-4
AREA=LW
20=(2W-4)W
20=2W^2-4W
2W^2-4W-20=0
2(W^2-2W-10)=0
W+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
W=(2+-SQRT[-2^2-4*1*-10])/2*1
W=(2+-SQRT[4+40])/2
W=(2+-SQRT44)/2
W=(2+-6.6)/2
W=8.6/2
W=4.3 ANS.
L=2*4.3-4=8.6-4=4.6 ANS.
PROOF:
4.3*4.6=20
20~20