Question

What is the explicit formula for the arithmetic sequence –7.5, –9, –10.5, –12, ....?

Answer 1

Answer: A

-7.5+(-1.5)(n-1)

Explanation:

i took the test on edge

Answer 2

`a_(n)` = - 1.5n - 6

Explanation:

Given that the sequence is arithmetic with n th term ( explicit formula

`a_(n)` = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Here a₁ = - 7.5 and d = - 9 - (- 7.5) = - 9 + 7.5 = - 1.5

`a_(n)` = - 7.5 - 1.5(n - 1) = - 7.5 - 1.5n + 1.5 = - 1.5n - 6