x coordinate of the vertex:
use the [tex] \frac{-b}{2a} [/tex] formula to get
[tex] x = \dfrac{-6}{2} = -3 [/tex]
y coordinate of the vertex:
plug the x value in the parabola:
[tex]y(3) = (-3)^2+6(-3)+5 = 9-18+5=-4 [/tex]
So, the vertex lies at [tex] (-3, -4) [/tex]
