Practice: Mike wants to build a rectangular pen with the using two parallel partitions and 600 feet of fencing. What dimensions will maximize the total area of the pen?

Practice: Mary needs to make an open rectangular box with square base from 48 ft.2 of material. What dimensions will result in a box with the largest possible volume?

Practice: Marcio is a farmer with 600 ft of fencing that wants a rectangular field that borders a river. What are the dimensions of the field that has the largest area?