The area of a rectangle is 25 square inches. Express the perimeter P(w) as a function of the width w, and state the domain of this function.
The only thing I'm not getting, is that in the back of the book, it says P(w) = 2w+(50/w)
Am I multiplying the 25 by two because it's square inches or where on earth is the 50 coming from? I'm not graded on the homework but I'd actually like to know why I'm doing this.
Edit: I'm just an idiot :D