Question

How do i solve this please help​

Answer 1

see explanation

Explanation:

(a)

`S_(n)` = 1 + 2 + 3 + 4 + 5 + ..... ( to n terms ), that is

∑ n ( for r = 1 to n )

∑ n =
`(1)/(2)` n(n + 1) =
`S_(n)`

(b)

`S_(30)` =
`(1)/(2)` × 30 × 31 = 465