A Set of Five Possible Wave Functions Is Given Below

Multiple Choice

A set of five possible wave functions is given below, where L is a positive real number.
Ψ1(x) = Ae^-x, for all x ψ2(x) = A cos x, for all x
Ψ3(x) =
Ψ4(x) =
Ψ5(x) =
Which of the five possible wave functions are normalizable? (There may be more than one correct choice.)

A) ψ1(x)
B) ψ2(x)
C) ψ3(x)
D) ψ4(x)
E) ψ5(x)