Consider three functions f,g,h on the set of integers Z. That is f: Z -> Z, g, Z-> Z, and h: Z -> Z, defined as follows:
f(x)=2x+2020
g(x) = x3 - x
h(x) = x4 -7
Which of these functions are one-to-one?
a) f
b) g
c) h
d) f and g
e) f and h
f) g and h
g) f and g and h
h) None of them