SOLUTION: The width of a rectangle is 3 ft less than the length. The area of the rectangle is 88 ft2. Find the length L and width W of the rectangle
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Question 1179368:  The width of a rectangle is 3 ft less than the length. The area of the rectangle is 88 ft2. Find the length L and width W of the rectangle 
Found 2 solutions by  MathLover1, greenestamps:
Answer by MathLover1(20850)   (Show Source): You can put this solution on YOUR website!
 
if the width of a rectangle is   less than the length, then we have 
....eq.1
if the area of the rectangle is , we have
........substitute 
...factor
=> or -> disregard negative solution for length
go to
....eq.1, substitute  
the length of the rectangle  and width of the rectangle 
 
Answer by greenestamps(13209)   (Show Source): You can put this solution on YOUR website!
 
Mentally, in five seconds or less: 88 = 11*8
Algebraically....
x = length
x-3 = width
The area (length times width) is 88:
Factor the quadratic:
The length is either 11 or -8; since -8 makes no sense, it is 11.  And then the width is 8.
Note that, in the formal algebraic solution, it was necessary to factor a quadratic equation by finding two numbers whose difference is 3 and whose product is 88; and that is what was required to solve the original problem mentally.
So the formal algebraic solution didn't make solving the problem any easier....
Nevertheless, it is a good exercise for a beginning algebra student to be able to set the problem up and solve it using formal mathematics.
 
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