What is the summation of terms from r=0 to n for the term n^2?

Answer 1

(n+1)^3 - n^3 = 3n^2 + 3n + 1
...
(0+1)^3 - 0^3 = 1

sum the lines

(N+1)^3 - 0 = 3 sum(n^2) + 3 sum(n) + (n+1)

you should be able to take from there

Answer 2

Sum as i goes from 1 to n of i^2 is [n(n + 1)(2n + 1)] / 6