The length of a rectangle is one foot more than twice its width the area of the rectangle is 66ft squared..find the demension?

Suppose we use x to represent the width of the rectangle in feet. The equation for the area of the rectangle can be written as
  66 = x(2x+1)
  2x^2 + x - 66 = 0    (subtract 66, put in standard form)
  x = (-1 ± √(1^2 - 4(2)(-66)))/(2(2))    (use the quadratic formula)
  x = (-1 ± √529)/4    (simplify)
  x = (-1 ± 23)/4    (simplify)
  x = {-6, 11/2}    (find the two solutions)

Only the positive solution makes sense as a dimension. The width (x) is 5.5 ft; the length (2x+1) is 12 ft.