What are the explicit equation and domain for an arithmetic sequence with a first term of 7 and a second term of 3?

An=a1+d (n-1)

a1=first term

d=common difference

n=which term

a1=7

a2=3

a2=3=7+d (2-1)

3=7+d (1)

3=7+d

-4=d

an=7-4 (n-1)

expanded

an=7-4n+4

an=11-4n

domain is the numbers you can use

we have to use numbers like 1,2,3,4,5

no 0

so we use natural numbers, that is the domain