Question

Find the 9^th term from the end (towards the first term) 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