Answer:
x = - [tex]\frac{b}{2}[/tex]
Step-by-step explanation:
Given a quadratic equation in standard form , that is
y = ax² + bx + c = 0 ; a ≠ 0
Then the x- coordinate of the vertex is
[tex]x_{vertex}[/tex] = - [tex]\frac{b}{2a}[/tex]
x² + bx + c = 0 ← is in standard form
with a = 1, b = b, thus
[tex]x_{vertex}[/tex] = - [tex]\frac{b}{2}[/tex]