Question

Find the 9^th term from the end of the A.P. 5, 9, 13,...,185.

Answer 1

Common difference, d, of the AP = 9 − 5 = 4
Last term, l, of the AP = 185
We know that the n^th term from the end of an AP is given by l − (n − 1)d.
Thus, the 9^th term from the end is
185 − (9 − 1)4
= 185 − 4 × 8
= 185 − 32
= 153