Question

The recursive formula for an arithmetic sequence is an = an-1 + d. If the common difference is -13 and a3 = 4, what is the value of a4?

Answer 1

$a_{n} = a_{(n-1)} + d$

where d is the common difference

Given that,

d = -13

$a_{3} = 4 \\a_{4} = a_{3} + d\\ =4 - 13 = -9$