Question 1151179
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            You can solve the problem in much shorter way, practically in your head, without solving quadratic equation.



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If W is the width, then the length is  L = (2W-1).


From the given area, you get the equation

    W*(2W-1) = 21.


Multiply both sides by 2. You will get

    2W(*2W-1) = 42.


So, the product of two numbers  (2w)  and  (2W-1) is 42 and their difference is 1.


It needs 2 seconds (and knowing the multiplication table) to guess/(to recognize)  the numbers:  2W = 7,  2W-1 = 6.


Hence, the width is 3.5 yards,  the length is 2*3.5-1 = 6 yards.    <U>ANSWER</U>
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Solved.