General form of a quadratic equation:
⇒ since the equation:
⇒ so:
To calculate the x-coordinate of the vertex
⇒use x =
<--- this is a property that helps you find the vertex of the
quadratic
x =
Since x = -1:
⇒ we can plug in this x-value into the original equation to find the y-
value
So the coordinate of the vertex: (-1,9)
Hope that helps!