SOLUTION: The area of a rectangular parcel of land is 720 square meters. The length of the land is 4 meters less than twice the width. A. Write an equation that can be used to find the dime

Algebra ->  Surface-area -> SOLUTION: The area of a rectangular parcel of land is 720 square meters. The length of the land is 4 meters less than twice the width. A. Write an equation that can be used to find the dime      Log On


   

Question 143143: The area of a rectangular parcel of land is 720 square meters. The length of the land is 4 meters less than twice the width.
A. Write an equation that can be used to find the dimensions of the land.
B. Solve the equation written in part A to find the dimensions of the land.
Answer by solver91311(24713) About Me  (Show Source):
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The area of a rectangle is given by length times width: A=LW

For this rectangle: L+=+2W+-4, so the area is then A=%282W-4%29W, but this is equal to 720%2Am%5E2, so:

%282W-4%29W=720
2W%5E2-4W-720=0
W%5E2-2W-360=0

Solving the quadratic gives you the width which can be substituted into L=2W-4 to calculate the length.

You can do your own arithmetic for part B. Hint: The quadratic factors quite neatly, but one of the roots will be negative. You can exclude that root since you are looking for a positive measure of length.