Question

The first term and the last term of an arithmetic progression are 'a' and 'T respectively, then the sum of its first 'n' terms is

Answer 1

Answer:

nT/2

Step-by-step explanation:

Given first term=a

we know that Tn=a+(n-1)d=last term

and also given last term =T

we know that sum of n terms =n/2(a+(n-1)d)

so,sum of n terms =n/2(T)

=nT/2

Answer 2

Answer:

Sn=a(n+l)\ 2

Step-by-step explanation:

hope it helps you