Question

10. |f an=3-21n, then find the common difference d.​

Answer 1

An = 3- 21n

when n=1

A¹ = 3-21 = 18

when n=2

A² = 3-21×2 = 2-42 = 39

d = A² - A¹ = 39 - 18 = 21

d= 21