Explain why the function is discontinuous at the given number a. (select all that apply.) f(x) = 1 x + 1 a = −1 lim x→−1 f(x) does not exist. f(−1) and lim x→−1 f(x) exist, but are not equal. lim x→−1+ f(x) and lim x→−1− f(x) exist, but are not equal. f(−1) is undefined. none of the above