What do i do when i get the question X cubed equals 729?

x times x times x = 729

Answer is 9

9 cubed is one of the answers to the question, and most probably the only one you need, but for the sake of completeness, you need the other two answers, which are complex numbers:

x= (9/2)(i(square root of 3)-9)

x= (9/2)(-i(square root of 3)-9)