Question

Which answer is the explicit rule for the sequence 12.5,11,9.5,8,6.5,5... ?

Answer 1

aₙ = 12.5 - 1.5(n - 1)

Explanation:

We use the general equation

aₙ = a₁ + d(n - 1)

aₙ is the term we want

a₁ is the first term (12.5)

d is the common difference (-1.5) as we go through the sequence we see a common difference of -1.5

n is the term number (if we wanted the third term n would be 3)