General form of a quadratic equation: [tex]ax^2+bx+c[/tex]
⇒ since the equation: [tex]-x^2-2x+8[/tex]
⇒ so:
To calculate the x-coordinate of the vertex
⇒use x = [tex]-\frac{b}{2a}[/tex] <--- this is a property that helps you find the vertex of the
quadratic
x = [tex]-\frac{(-2)}{2*(-1)} =-1[/tex]
Since x = -1:
⇒ we can plug in this x-value into the original equation to find the y-
value
[tex]y =-(-1)^2-2(-1)+8=-1+2+8=9[/tex]
So the coordinate of the vertex: (-1,9)
Hope that helps!
