Answer
a) yes; b) no
Work Step by Step
The function is one-to-one if each $y$ corresponds only to one value of $x$.
a) The function $f(x)$ is one-to-one because it respects the above rule.
b) The function $f(x)$ is not a one-to-one function because there is a value of $y$ which corresponds to more than one value of $x$:
$f(1)=4$ and $f(6)=4$
