4.1 number 18

In Exercises 14-37, find the interval(s) where the function is increasing and the interval(s) where it is decreasing. 14. f(x) = 4 - 5x 15. f(x) = 3x + 5 16. f(x) = x2 - 3x 17. f(x) = 2x2 + x+1 18. f(x) = x3 - 3x2 19. g(x) = x - x3 20. f(x) = x3 - 3x + 4 21. a(x) = 13 + 372 + 1