What is the range of this quadratic function?

Answer:
(negative infinity, 4]
Step-by-step explanation:
Reminder: the range is all the possible y values the function can get by plugging in x values.
Since this is a downward opening parabola, it won't have a lower boundary, which means that the answer must be (negative infinity, 4]
We can further check that's correct by seeing that the parabola has its vertex at 4, which is written in the answer.
That means the correct answer must be (negative infinity, 4]