Mathematics: Calculate s4 for the sequence defined by

Calculate s4 for the sequence defined by - id4290566, cancerbaby209

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10.03.2022

The correct answer option is 36.

Step-by-step explanation:

We know that,

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

$S_n=\frac{n(a_1+a_n)}{2}$

where 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:

$S_4=\frac{4(15+3)}{2}$

$S_4=\frac{72}{2} \\\\S_4=36$

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

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