Question

given a=8,an=62,sn=210find n and d​

Answer 1

Given data,

a = 8

a_n=62

a_n = a +(n-1)d

62 = 8+(n-1)d

or, (n-1)d=54

Sn = 210

n/2[2a+(n-1)d] =210

or, n[2x8+(n-1)d] = 420

or, n[16+54] = 420

or, 70n=420

or, n = 6

Then,

(n-1)d=54

or, 5d=54

» d = 54 / 5