4. let x = {1,2,3,4} and y = {5,6,7,8,9}

given two functions:
f= {(1,7), (2,5), (3,6), (4,7)} & g= {(1,5), (2,6), (1,8), (2,9), (3,7)}

a) is fa function? if yes, what is the domain and range?

b) is g a function? if yes, what is the domain and range?

c) what is f(2)?

d) if f(x) = 7, what is the value of x?