Question 106613
You have the right idea, but I'm not sure where you got {{{s=5.120}}} from. 


{{{s^3=800}}} Start with the given equation



{{{root(3,s^3)=root(3,800)}}} Take the cube root of both sides. This will undo the exponent of 3




{{{s=root(3,800)}}} Take the cube root of {{{s^3}}} to get {{{s}}}

{{{s=9.283}}} Take the cube root of 800 to get 9.283


So the side length is {{{s=9.283}}}