Answer:
vertex = (- 1, - 10 )
Step-by-step explanation:
given the equation of a parabola in standard form
y = ax² + bx + c : a ≠ 0
Then the x-coordinate of the vertex is
[tex]x_{vertex}[/tex] = - [tex]\frac{b}{2a}[/tex]
y = - 5x² - 10x - 15 is in standard form
with a = - 5, b = - 10 and c = - 15, hence
[tex]x_{vertex}[/tex] = - [tex]\frac{-10}{-10}[/tex] = - 1
substitute x = - 1 into the equation for y
y = - 5(- 1)² - 10(- 1) - 15 = - 5 + 10 - 15 = - 10
vertex = (- 1, - 10 )
