The explicit rule for a sequence is a_n=7(−4)^n−1 .

n

step-by-step explanation:

if you are saying purchasing 3 social media ads and one newspaper ad counts as one purchase then there are:

6 purchases

if you are asking how many of each then:

18 social media ads

6 newspaper ads

let m = monomial

let t = trinomial

so, m times t = t.

monomial times a trinomial = another trinomial.