Question

Find the sum to n terms of the series whose n'th term is n(n+3)?

Answer 1

Answer:

∑ n(n+3)

∑n

2

+3n

∑n

2

+3∑ n

6

n(n+1)(2n+1)

+

2

3n(n+1)

2

n(n+1)

[

3

2n+1

+3]