Question 456786
You want to build a rectangular fence which is 4 feet longer than it is wide. You want the area enclosed by the fence to be 35 square feet. How wide is the fence (we are asking for the smaller side length)? 

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Let width = "x".
Then length = "x+4".
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Solve: x(x+4) = 35
x^2+4x-35 = 0
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Use the quadratic formula to solve for "x":
x = [-4 +- sqrt(16-4*-35)]/2
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x = [-4 +- sqrt(156)]/2
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x = [-4 + sqrt(4*39)]/2
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Positive solution:
x = [-4+2*sqrt(39)]/2 ~ 4.25 ft. (width)
x+4 ~ 8.25 ft. (length)

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Cheers,
Stan H.
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