Answer:
x= -2/3
Step-by-step explanation:
The best way to solve this problem is through completing the square so
[tex]y=-6-4x-3x^2\\y=-3x^2-4x-6\\y=-3(x^2+\frac{4}{3} x)-6\\y=-3(x^2+\frac{4}{3} x+\frac{4}{9} -\frac{4}{9})-6\\y=-3(x^2+\frac{4}{3} x+\frac{4}{9})-6+\frac{4}{3} \\y=-3(x+\frac{2}{3} )^{2} -\frac{14}{3} \\[/tex]
Vertex is at
[tex](-\frac{2}{3} ,-\frac{14}{3})[/tex]
Axis of symytry is x= -2/3
