Question

a=2,d=7,a4= 23 find n and sn.​

Answer 1

Answer:

Given

a=2

d=7

A4=23

An=a+(n-1)d

23=2+(n-1)7

23-2=(n-1)7

21/7=(n-1)

3=n-1

n=3+1

n=4

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

S4=4/2[2×2+(4-1)7]

S4=2[4+21]

S4=2×25

S4=50

n=4 and sn=50