If f (x)  = x when x < 0

            = x² when x>0, then  f(x) is

   Lt         x - [x] , where k is an integer, is equal to
 x→ k+

. Then the value of k is.

    Lt       [x]  is equal to.
 x→ 2^-

  then       Lt   f(x) is
                                                             x → ∞

If f (2) = 4 and f' (2) = 4, then equals.