Prove this formla?

Question

Prove the formula for this:
1^2 + 2^2 + 3^2 + ... +n^2

Answer 1

1^2 + 2^2 + 3^2 + ... +n^2 = n(n+1)(2n+1)/6

Answer 2

skip about 2 or 3 screens down in the following link, to where it says to prove the sum of squares, start with
(n+1)³ = n³ + 3n² + 3n + 1. study the proof of sum of integers above it, then try to apply it.