1. A ________ ________ is a quotient of polynomial functions.
2. When f (x) → ± ∞ as x → a from the left or the right, x = a is a ________ ________ of the graph of f.
3. When f (x) → b as x → ± ∞ y = b is a ________ ________ of the graph of f.
4. The graph of f (x) = 1 / x is a ________.