Question

The first and last term of an ap are 1 and 11 respectively. If the sum of its yerms is 36. Find the number of terms

Answer 1

a= 1
L = 11

Sn = 36
=> n( a +L) /2 = 36
=> n(1+11)= 72
=> n *12 = 72
=> n = 6


No.of terms = 6

Answer 2

a=1
l=11

sn=36
sn=n/2(a+l)=36
n(1+11)=36*2
n*12=72
n=72/12
n=6