Question

P(x)=-x^2+620x-34100 Will the graph of this function open up or down

Answer 1

Is "a" positive or negative?

Answer 2

He is talking about the coefficient of x^2

Answer 3

Whenever you want to see if a parabola is up or down, just look are the ax^2 component. You can ignore the rest.

If you have -ax^2, then it's facing down. If it's +ax^2, then it faces up.