Answer
$ f(x)=x^2+2$ is not one-to-one, $ f(x)=x^2+2$ is one-to-one on $[0,\infty)$.
Work Step by Step
$ f(x)=x^2+2$ is not one-to-one, because, for example $ f(-1)=f(1)$ and $-1\neq 1$. $ f(x)=x^2+2$ is one-to-one on $[0,\infty)$ (the right side of the parabola).
