Also for 1 ∈ N, we
have f (1) = 1 Example 11  Show that the function f : R → R,
defined as f (x) = x2, is neither one-one nor onto Solution  Since f (– 1) = 1 = f (1), f is not one-
one Also, the element – 2 in the co-domain R is
not image of any element x in the domain R
(Why