Prove that 1^2 2^2 3^2 n^2= (n(n 1)(2n 1))/6

Prove that 1^2 2^2 3^2 n^2= (n(n 1)(2n 1))/6

Prove that 1^2+2^2+3^2++n^2= (n(n+1)(2n+1))/6