Check the injectivity and surjectivity of the following functions:
(i) `f : N ->N`given by `f(x)=x^2`
(ii) `f : Z-> Z`given by `f(x)=x^2`
(iii) `f : R ->R`given by `f(x)=x^2`
(iv) `f : N-> N`given by `f(x)=x^3`
(v) `f : Z → Z` given by `f(x) = x^3`