(2,3)(4,5)(6,7)(8,9) represents a function

(2,3)(4,5)(6,7)(8,9) represents a function

Domain is the x-values:
x = (2, 4, 6, 8)

Range is the y-values:
y = (3, 5, 7, 9)

The function y, or f(x) is:
y = x + 1 where x = (2, 4, 6, 8)

Test this function for x = 2:
y = 2 + 1
y = 3

Test this function for x = 4:
y = 4 + 1
y = 5

Test this function for x = 6:
y = 6 + 1
y = 7

Test this function for x = 8:
y = 8 + 1
y = 9