Question

the first term of am A.P is 6 and the common difference 3 respectively. find S2

plz fast...​

Answer 1

Answer:15

Step-by-step explanation

In an AP

a=6

d=3

Sn=n/2(2a+(n-1)d

S2=2/2(2*6+(2-1)3)

=1(12+3)

=1(15)

S2 =15

Answer 2

Answer:

The sum of first 2 terms of the AP is 15.

Step-by-step-explanation:

NOTE: Kindly refer to the attachment first.

We have given that, for an AP,

$\sf\:a\:=\:6,\:\:d\:=\:3$.

We have to find, $\sf\:S_{2}$.

We know that,

$\boxed{\red{\sf\:S_{n}\:=\:\frac{n}{2}\:[\:2a\:+\:(\:n\:-\:1\:)\:d\:]}}\:\:\:-\:-\:-\:[\sf\:Formula\:]\\\\\implies\sf\:S_{2}\:=\:\frac{\cancel2}{\cancel2}\:[\:2\:\times\:6\:+\:(\:2\:-\:1\:)\:\times\:3\:]\\\\\implies\sf\:S_{2}\:=\:1\:\times\:[\:12\:+\:1\:\times\:3\:]\\\\\implies\sf\:S_{2}\:=\:12\:+\:3\\\\\implies\boxed{\red{\sf\:S_{2}\:=\:15}}$

Additional Information:

1. Arithmetic Progression:

1. In a sequence, if the common difference between two consecutive terms is constant, then the sequence is called as Arithmetic Progression ( AP ).

2. $\sf\:n^{th}$ term of an AP:

The number of a term in the given AP is called as $\sf\:n^{th}$ term of an AP.

3. Formula for $\sf\:n^{th}$ term of an AP:

$\boxed{\pink{\sf\:t_{n}\:=\:a\:+\:(\:n\:-\:1\:)\:d}}$

4. The sum of the first n terms of an AP:

The addition of either all the terms of a particular terms is called as sum of first n terms of AP.

5. Formula for sum of the first n terms of A. P. :

$\boxed{\red{\sf\:S_{n}\:=\:\frac{n}{2}\:[\:2a\:+\:(\:n\:-\:1\:)\:d\:]}}$