Question

Choose all of the following equations that have a vertex that is the maximum point of the parabola. More than one answer may be chosen.

y = −4x2 + 8x − 19

y = −x2 − 7x + 1

y = 8x2 − 6x + 128

y = 3x2 + 9x − 4

Answer 1

All vertices are either maximum or minimum of a parabola.
Parabolas that have a maximum are those that are concave downwards.
You can spot these by observing the sign of the leading coefficient (the coefficient of the x^2 term).
If the leading coefficient is positive, the parabola is concave upwards (i.e. has a minimum.)
If the leading coefficient is negative, the parabola is concave downwards (i.e. has a maximum.)
From the above list, I spot two of each.

Answer 2

So the first and second.