Hi
the vertex form of a Parabola opening up(a>0) or down(a<0),
where(h,k) is the vertex and x = h is the Line of Symmetry
Y= -4x^2-12x-3 |completing Square of ax^2 + bx + c
y = -4(x - (-3/2))^2 + 9 - 3 |Note: -3/2 = -b/2a
V(-3/2, 6), a=-4<0. Opens Downward, axis of symmetry x = -3/2
y = -4(x+3/2)^2 +6
0 = -4(x+3/2)^2 +6
4(x+3/2)^2 = 6
(x+3/2)^2 = 6/4
x = -3/2 ± √6 / 2 roots
domain All real Numbers
range [6,−∞)