Which of the following statements about Laplace transform is true?
1) The integral that defines the Laplace transform has to converge.
2) If F(s) represents the Laplace transform of a function f(t), that is Lf(t) = F(s), then we say f(t) is the inverse Laplace transform of F(s).
3) In evaluating inverse transforms, it always happens that a function of s under consideration matches exactly the form of a Laplace transform F(s) given in a table.
4) If f is piecewise continuous on [0, infinity) and of exponential order, then Lf(t) exists for s > c.