Type the correct answer in each box. Use numerals instead of words. If necessary, use / for the fraction bar(s). Find the factors of function f, and use them to complete this statement. f ⁡ ( x ) = 2 ⁢ x 4 − x 3 − 18 ⁢ x 2 + 9 ⁢ x From left to right, function f has zeros at x = , x = , x = , and x = .