Part b: the area of a rectangle is (81x2 - 4y2) square units. determine the dimensions of the rectangle by factoring the area expression completely. show your work.

The given expression for the area, 81x² - 4y², is a difference of two squares. The first term is the square of 9x and the second term is the square of 2y. The factors of this difference and the therefore the dimensions of the rectangle are, 9x - 2y and 9x + 2y.