Question

Calculate s4 for the sequence defined by

Answer 1

C is the correct one so 36 :)

Answer 2

The correct answer option is 36.

Explanation:

We know that,

the sum of the first n terms of an Arithmetic Sequence is given by:

`S_n=(n(a_1+a_n))/(2)`

where
`n` is the number of terms,

`a_1` is the first term of the sequence; and

`a_ n`is the first term of the sequence.

So for
`a_n=(19-4n)`,

`a_1=19-4(1)=15\\\\a_4=19-4(4)=3`

Putting these values in the formula to get:

`S_4=(4(15+3))/(2)`

`S_4=(72)/(2) \\\\S_4=36`

Therefore, the 4th term of the given sequence is 36.