For f(x) = -2x^2 - 8x-2
a. Determine whether the parabola opens up or down
b. Find the vertex
how can determine whether the parabola opens up or down and find the vertex? Thanks in advance.
$\displaystyle f(x) = ax^2 + bx + c$
if the leading coefficient, $\displaystyle a$ , of the quadratic is positive, the parabola opens upward
if the leading coefficient, $\displaystyle a$ , of the quadratic is negative, the parabola opens downward
the x-value of the vertex is $\displaystyle x = \frac{-b}{2a}$