Given a sequence, find the sum of the series. This can be done by simplifying the equation to a more generic series.

1. Polynomials Q6

2. Qn: Sum of squares of nos.
(a) 9455 (b) 5456
(c) 3468 (d) 4892
What is the sum of 12 + 32 + 52 …….312?

3. Soln: Sum of squares of nos.
This Expression is same as (12 + 22 + 32 + 42 + 52 …….302 + 312) – (22 + 42 + 62
….302)
= (12 + 22 + 32 + 42 + 52 …….302 + 312) – 4(12+ 22 + 32 ….152)
12 + 22 + 32 +.......... + n2 =
n(n+1)(2n+1)
6
, for all n > 1.
Expresssion =
31 x 32 x 63
6
-
4 x 15 x 16 x 31
6
=
31 x 32 x 33
6
= 31 × 11 × 16 = 5456
Answer choice (b)
What is the sum of 12 + 32 + 52 …….312?