1st part: Ltf_(1) and f_(2) be two entire functions. since both f_(1) and f_(2) are entire function, both are well-defined on the complen plame (C and also hoth heve derivatives for all z inCsince f_(1) and f_(2) are well defined the function f_(1)@f_(2)(z) is well defined by using chain rule of differentiation for evory z inC (f_(1)@f_(2))^(')(z)=(d)/(dz)(f_(1)(f_(2)(z)))=f_(1)^(')(f_(2)(z))(f_(2)^(')(z)) and ... See the full answer