## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$$A=w^2+3w$$
The perimeter is the sum of the side lengths. Thus, the perimeter is: $$w+3+w+3+w+w \\ 4w+6$$ Using the equation for the area of a rectangle, we find: $$A=w(w+3) \\ A=w^2+3w$$