19. Let x f x xe−x and p(x) = ... be the Maclaurin series of f(x), then a4 = . (A) (B) (C) (D) (E)

23. Define the function . Which of the following statement is correct? (A) Function f derives its absolute maximum at point x = −1 (B) Function f derives its absolute maximum at point x = 0 (C) Function f derives its absolute maximum at point x = 1 (D) Function f derives its absolute minimum at point x = −1 (E) Function f does not have absolute maximum or minimum value