Question

Prove that 1^2+2^2+3^2+..........+n^2=n(n+1)(2n+1)/6,n belongs to natural numbers

Answer 1

First consider the series as P(n) then proved it that it is true for n=1.after it ....I post a picture.I wish you can understand it.... If you felt any confusion in my handwriting please tell me.....after it was proved for k+1 we can consider it is true for natural number