Answer
Not one-to-one.
Work Step by Step
A function is one-to-one if different inputs have different function values.
Algebraically written, $x_{1}\neq x_{2}\Rightarrow f(x_{1})\neq f(x_{2})$
Here, we can find a pair of x-values from the domain of f for which this is not true.
For instance, $-1\neq 1,$ but
$f(-1)=3-(-1)^{2}=2$
$f(1)=3-1^{2}=2$.
Not one-to-one.
