A
Given a quadratic in standard form : y = ax² + bx + c ( a ≠ 0 ), then
The x-coordinate of the vertex is
= -
y = - 3x² + 2x - 7 is in standard form
with a = - 3, b = 2 and c = - 7, hence
= -
=
Substitute this value into the equation for y-coordinate
y = - 3 ()² + 2 (
) - 7
= - +
-
= -
vertex = ( , -
) → A