Question

Which is a correct statement about the function f (x) = 5x from the set

of integers Z to the set of integers?

Answer 1

f(x) is 1-1 but not onto.

$\forall x_1, x_2\in \Z$, if $f(x_1)=f(x_2),$ then $x_1=x_2.$ The function $f (x) = 5x$  from the set of integers $\Z$ to the set of integers is 1-1.

If $y=1,$ we cannot find $x\in \Z$ such that $y=5x=1.$ The function $f (x) = 5x$  from the set of integers $\Z$ to the set of integers is not onto.