- #1
sooyong94
- 173
- 2
Homework Statement
Homework Equations
Summation
The Attempt at a Solution
I know I could have simplified (3n-2)^3 +(3n-1)^3 -(3n)^3 and put the formulas in but I wonder is there any other method (I was thinking about grouping the terms, but to no avail) to work this out.