The nth term of an AP is (7 – 4n). Find its common difference.

Question

Philoid · Accepted Answer

n^th term of an AP = a_n = 7 - 4n

Common difference (= d) of an AP is the difference between a term and its preceding term.

∴ d = a_n - a_{n - 1}

= (7 - 4n) - (7 - 4(n - 1))

= 7 - 4n - 7 + 4n - 4

= - 4

∴ Common difference = - 4.