Question

What is the 23rd term of the arithmetic sequence where a1 = 8 and a9 = 48 ?

Answer 1

$a_1=8;\ a_9=48\\\\a_9-a_1=8d\\\\8d=48-8\\8d=40\ \ \ |divide\ both\ sides\ by\ 8\\d=5\\\\a_{23}=a_1+22d\\\\a_{23}=8+22\cdot5=8+110=118\\\\Answer:\boxed{a_{23}=118}$