Question

Find the sum of 13th term and 23rd term of an AP: 3, 15, 27, 39, ………. .​

Answer 1

Answer:

$414$

Step-by-step explanation:

$a = 3 \\ d = 15 - 3 = 12 \\ \\ n = 13 \\ an = a + (n - 1)d \\ a13 = 3 + (13 - 1)12 \\ a13 = 147 \\ \\ n = 23 \\ an = a + (n - 1)d \\ a23 = 3 + (23 - 1)12 \\ a23 = 267 \\ \\ sum \: of \: 13th \: and \: 23rd \: term \\ = 147 + 267 \\ = 414$