Question

Explain what is meant by the given formula:
a1=12
an=an-1-8

Answer 1

Explanation:

that this is an arithmetic sequence of terms, where every term is created by adding (or subtracting) to/ from the previous term.

a1 is the starting value = 12

then

a2 = a1 - 8 = 12 - 8 = 4

a3 = a2 - 8 = a1 - 8 - 8 = -4

every term is 8 less than the previous term.

so, we see, we can express the nth term of the sequence also in terms of a1 :

an = an-1 - 8 = a1 + -8×(n-1) = a1 - 8×(n-1)