Depends. Are you allowed to use your calculator? If not, do you know enough Calculus to take a first derivative? Or did you want the long hand process for taking cube roots? I can get you a link to the process, but it is as ugly as a mud fence. Best, especially with a relatively small radicand like 320, is to just guess and check until you get it as precise as you like. Still it is a long and laborious process with little value to anyone, particularly in this age of computers.
John
My calculator said it, I believe it, that settles it
