- #1
Duderonimous
- 63
- 1
Homework Statement
A problem out of "What is Mathematics" by Courant and Robbins
Prove that
1[itex]^{2}[/itex]+3[itex]^{2}[/itex]+...+(2n+1)[itex]^{2}[/itex] =
[itex]\frac{(n+1)(2n+1)(2n+3)}{3}[/itex]
Homework Equations
Prove this using
1[itex]^{2}[/itex]+2[itex]^{2}[/itex]+...+n[itex]^{2}[/itex] =
[itex]\frac{n(n+1)(2n+1)}{6}[/itex]
The Attempt at a Solution
I tried seeing how the ratio of 1st, 2nd, and 3rd terms of each sequence change as one goes on in the sequence. Like 1/1 =1, 5/10 =.5, 14/35=.4, 30/84=.357142857143... I didn't get much insight there. I know I have to start with the second equation and divide or multiply it by something to get the first equation. Cant figure out that term would be. Any help would be great! Thanks.