Answer:
see explanation
Step-by-step explanation:
A
the common difference d of the arithmetic sequence is
d = a₂ - a₁ = 79 - 83 = - 4
B
the explicit formula of an arithmetic sequence is
[tex]a_{n}[/tex] = a₁ + (n - 1)d
where a₁ is the first term and d the common difference
here a₁ = 83 and d = - 4 , then
[tex]a_{n}[/tex] = 83 - 4(n - 1) = 83 - 4n + 4 = 87 - 4n
