REALLY EASY MATH 50 POINTS please help I really need it

When Isabel began her book-selling business, she stored her inventory in her garage. Now that her business has grown, she wants to rent warehouse space. Lisa owns a large warehouse nearby and can rent space to Isabel. The area of the warehouse is 8,100 square feet. Lisa is willing to rent Isabel as little as 100 square feet of the space or up to as much as the entire warehouse. Her only requirement is that all spaces must be square. The total length of each row of bookshelves will be of the length of the storage space.

b) Write a function that expresses f(x). (10 points)

c) Graph the function. (10 points)

ANY ABSURD ANSWERS WILL BE REPORTED