Aknitter wants to make a rug for a dollhouse. the length of the rug will be 2 inches
more than its width. the total area of the rug (in square inches) based on the width
w of the rug (in inches) is given by
a(w) = w (2 + w)
if the desired area of the rug is 15 square inches, what is the width of the rug, in
inches?