Question

what is the sum of an A.P.​

Answer 1

Answer:

Sn-n/2[2a+n-1(d)]

Sn-n/2[t1+tn]

Answer 2

Step-by-step explanation:

The sum of n terms of AP is the sum(addition) of first n terms of the arithmetic sequence. It is equal to n divided by 2 times the sum of twice the first term – 'a' and the product of the difference between second and first term-'d' also known as common difference, and (n-1), where n is numbers of terms to be added.