What number completes the sequence below? Enter your answer below. 9 ➡️ 14
12 ➡️ 17
15 ➡️ 20
18 ➡️ ?

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

Me. i can't figure out this question. give an explanation too. .

Which of the following parabolas opens down?