Question

What is the explicit formula for this sequence?
-9,-3,3,9,15

Answer 1

Answer: A

Explanation:

Normally in choice questions, I would choose to substitute the values into the formulas but I think it is better if I explain to you.

In a sequence, if the numbers increase by d each time and the first number in the sequence is
`a_(1)`, then the explicit formula is
`a_(1)` + (n - 1)d when n is the order of the number in the sequence, like n = 1 for the first number, n = 2 for the second number and so on. Using this, we get that the answer to this problem is
`a_(n)` = -9 + (n - 1)6 so the answer is A