Michael J. answered 07/10/15
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Effective High School STEM Tutor & CUNY Math Peer Leader
The area of any rectangle is length times width.
Let width = x
Let length = 4x - 1
Area = 60 ft2
Write an equation that uses the area and the variables.
x(4x - 1) = 60
4x2 - x = 60
Subtract 60 on both sides of the equation.
4x2 - x - 60 = 0
Factor the left side of the equation using FOIL, if possible.
(4x + 15)(x - 4) = 0
Set the factors equal to zero.
4x + 15 = 0 and x - 4 = 0
x = -15/4 and x = 4
We have two solutions. Since we cannot have a negative value for dimensions, we accept the positive value of x.
x = 4
Finally, we substitute this value of x into the dimensions.
width = 4 feet
length = 15 feet
Michael J.
07/10/15