Question 530685
The x-coordinate of the vertex can be found by:
{{{x = (-b)/2a}}} where: a = -4 and b = -16.
{{{x = (-(-16))/2(-4)}}} Evaluate.
{{{x = 16/(-8)}}}
{{{x = -2}}} Now substitute this value of x into the given quadratic equation to find the value of the y-coordinate.
{{{y = -4(-2^2)-16(-2)-11}}} Evaluate.
{{{y = -16+32-11}}}
{{{y = 5}}}
The vertex is at (-2,5)
Here's the graph:
{{{graph(400,400,-5,5,-5,10,-4x^2-16x-11)}}}