Consider the functions f (x) = x³ − 7x² − 5x + 4 and f'(x) = 3x² − 14x − 5. Given that f is increasing where f'(x) > 0 and f is decreasing where f'(x) < 0, find where f is increasing and where f is decreasing. Because polynomials are continuous over their domain, all endpoints are included in the interval describing increasing/decreasing. In general, however, the numbers at the endpoints must be tested separately to determine if they should be included in the interval describing where a function is increasing or decreasing.