Question

The second term of an arithmetic sequence is –39. The rule a, - a-1 +12 can be used to find the next term of the

sequence. What is the explicit rule for the arithmetic sequence?

Answer 1

a 2 = -39

a 2 = a 1 + 12

- 39 = a 1 + 12

a 1 = - 39 - 12

a 1 = - 51 ( first term )

The common difference is : d = 12

The explicit rule for the arithmetic sequence:

a n = a1 + ( n - 1 ) d

a n = -51 + ( n - 1 ) · 12

Explanation: