**If a1,a2,a3,…,an is an arithmetic progression with common difference d, then evaluate the following expression.**

###### Answers:

Since a_{1},a_{2},a_{3},…,an is an arithmetic progression with common difference d

d = a_{2} -a_{1} = a_{3}-a_{2} = a_{4} – a_{3 }= ……. = a_{n} – a_{n-1 }