Question

What is the 30th term of the arithmetic series 4, 7, 10, …? 88 89?

Answer 1

a1 = 4; a2 = 7; a3 = 10
d = a2 - a1 -> d = 7 - 4 = 3
an = a1 + (n-1) d -> an = 4 + (n-1) * 3 = 4 + 3n - 3n + 1
[an = 3n + 1]
a30 = 3 * 30 + 1 = 90 + 1 = 91
Answer: a30 = 91