Question

Given the sequence {2,-1,-4,-7} find a25

Answer 1

-70

Explanation:

This is an arithmetic progression with a difference of -3

Formula for AP is

Sn = a + (n - 1) d

Where

a is the first term, 2

n is the term we're looking for, 25

d is the arithmetic difference, -3

a25 = 2 + (25 - 1) -3

a25 = 2 + (24) -3

a25 = 2 - 72

a25 = -70