Question

Find the sum of the first six terms of the sequence.


S6 = ⇒ 84

Answer 1

84

Explanation:

Correct on edge 2021!!!

Answer 2

Explained below.

Explanation:

Consider the series is a set of first 6 natural numbers.

Sum of first n terms is:

`\text{Sum of n terms}=(n(n+1))/(2)`

`\text{Sum of first 6 terms}=(6(6+1))/(2)`

`=3*7\\=21`

Consider the series is an arithmetic sequence.

Sum of first n terms is:

`S_(n)=(n)/(2) [2a+(n-1)d]`

Here,

a = first term

d = common difference

Consider the series is an geometric sequence.

Sum of first n terms is:

`S_(n)=(a_(1)\cdot(1-r^(n)))/((1-r))`

Here,

a₁ = first term

r = common ratio