$f$ is a function mapping $x$ axis to plane $V$ defined by if $P(x,0)$ then $f(P) = (x,x^2)$ ?
I am not so sure for my following answer :
to show that $f$ is surjective, for every $A(x,x^2)$ there exist $B(x',y')$ element $x$ axis such that $f(B) = A)$.
it is obtained that $x' = x$ and $y'$ equals the square root of $x$.