Question

write the formula to find the sum of n terms of an a.p​

Answer 1

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

hope this helps

Answer 2

Sum of first n terms of an AP:

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

The sum of n terms is also equal to the formulawhere l is the last term:

S=(n/2)(a+l)