Question

Find the sum of first term of the sequence 1,2,4,8,12

Answer 1

The right solution is "18". A further explanation is given below.

Explanation:

The given series is:

1,2,4,8,12

Here,

First term,

a₁ = 1

Second term,

a₂ = 2

Last term,

n = 12

Now,

The sum of the sequence will be:

⇒
`S_n = (n ( a 1 + a 2 ) )/(2)`

On substituting the values, we get

⇒
`=(12(1+2))/(2)`

⇒
`=(12* 3)/(2)`

⇒
`=(36)/(2)`

⇒
`=18`