## anonymous 4 years ago prove sigma n^2=n(n+1)(2n+1)/6

1. anonymous

i know!

2. anonymous

that is $\sum_{1}^{n}$n^2

3. anonymous

then tell?

4. anonymous

NCERT

5. anonymous

For reference, you should not use the same variable for the upper limit as you do in the expression. Instead, say $\sum_{k=1}^n\space k^2$

6. anonymous

Do you mean prove it or derive it? It can be proved with induction.

7. anonymous

sorry i meant derive it?

8. anonymous

http://www.trans4mind.com/personal_development/mathematics/series/sumNaturalSquares.htm In the first proof I don't get this part "...Because $$Δ_3$$ is a constant, the sum is a cubic of the form..."