What is the explicit formula for arithmetic sequence {-20, - 5, 10, ... }? Use f (n) where is 1, 2, 3, and so on.

A: f (n) = - 20 - 15 (n - 1)

B: f (n) = - 20 + 15 (n - 1)

C: f (n) = 20 - 15n

D: f (n) = 20 + (n - 1)

Question

Mathematics

Marlene Coffey

22 September, 00:58

What is the explicit formula for arithmetic sequence {-20, - 5, 10, ... }? Use f (n) where is 1, 2, 3, and so on.

A: f (n) = - 20 - 15 (n - 1)

B: f (n) = - 20 + 15 (n - 1)

C: f (n) = 20 - 15n

D: f (n) = 20 + (n - 1)

+4

Answers (1)

Know the Answer?

Grady Andrade · Answer 1

Answer: B

Work:

Since the general formula of an arithmetic sequence is f (n) = (the first term) + (common difference) * (n-1), you just plug in what was given to you in the problem to that equation. The first term is - 20 and the common difference is + 15 since the the increase from one term to the next is 15. Doing so produces the equation f (n) = - 20 + 15 (n-1), which is choice B.

What is the explicit formula for arithmetic sequence {-20, - 5, 10, ... }? Use f (n) where is 1, 2, 3, and so on.A: f (n) = - 20 - 15 (n - 1)B: f (n) = - 20 + 15 (n - 1)C: f (n) = 20 - 15nD: f (n) = 20 + (n - 1)

What is the explicit formula for arithmetic sequence {-20, - 5, 10, ... }? Use f (n) where is 1, 2, 3, and so on.

A: f (n) = - 20 - 15 (n - 1)

B: f (n) = - 20 + 15 (n - 1)

C: f (n) = 20 - 15n

D: f (n) = 20 + (n - 1)