Question 1:
a(n) = 2 n - 3
a(1) = 2 (1) - 3 = 2 - 3 = -1
a(2) = 2 (2) - 3 = 4 - 3 = 1
a(3) = 2 (3) - 3 = 6 - 3 = 3
a(4) = 2 (4) - 3 = 8 - 3 = 5
a(5) = 2 (5) - 3 = 10 - 3 = 7
The first five terms are shown above in bold.
Therefore the Domain of this relationship is the Positive Integers {1, 2, .....}
and the Range is the following subset of odd integers: {-1, 1, 3, 5, 7, ...}
Question 2:
a(n) = - 5 n + 20
a(1) = - 5 (1) + 20 = - 5 + 20 = 15
a(2) = - 5 (2) + 20 = -10 + 20 = 10
a(3) = - 5 (3) + 20 = - 15 + 20 = 5
a(4) = - 5 (4) + 20 = - 20 + 20 = 0
a(5) = - 5 (5) + 20 = - 25 + 20 = -5
Therefore the Domain of the relationship is again the set of Positive Integers {1, 2, 3, 4, ...}
and the Range is the set of integers which are multiples of five smaller than or equal to 15. { y = multiple of five <= 15}