What are the explicit equation and domain for an arithmetic sequence with a first term of 7 and a second term of 3?
a. an = 7 − 4(n − 1); all integers where n ≥ 1
b. an = 7 − 4(n − 1); all integers where n ≥ 0
c. an = 7 − 3(n − 1); all integers where n ≥ 1
d. an = 5 − 3(n − 1); all integers where n ≥ 0

I am detailing it to show you how to calculate an explicite equation

Arithmetic Progression First term 7 , second 3 hence d=3-7 = - 4

n=Term rank  ==>║    1     2     3     4     5     6     7n
Value         >║    7     3    -1    -5    -9   -13   -17

a(n) (sub Notation║    a₁   a₂    a₃    a₄    a₅    a₆    a₇a(n)

Term 1 = a₁ = 77-4(0)
Term 2 = a₂ = 37-4(1)
Term 3 = a₃ = -17-4(2)
Term 4 = a₄ = -57-4(3)
Term 5 = a₅ = -97-4(4)
Term n =  a(n) 7-4(n-1)
So A. an = 7 − 4(n − 1); all integers where n ≥ 1