Question

(If 'a' is first term and 'a'n is the last term of an AP, then what is the sum of nth term?​

Answer 1

Answer:

Step-by-step explanation:

$s_{n} =\frac{n}{2} (a+a_{n} )$

Hence proved

Answer 2

Step-by-step explanation:

we know, S(n) = n/2 * [a+l]

Here, a = a

l = an

therefore,  S(n) = n/2 * [a+an]

Hope it helps :)

Have a good day.