Answer
See the graph
Work Step by Step
$f(x)=-2x^2-10x$
Find the axis of symmetry and the coordinates of the vertex.
$x=\frac{-b}{2a}=\frac{-(-10)}{2.(-2)}=\frac{-5}{2}$
The axis of symmetry is $x=\frac{-5}{2}$. So the x-coordinate of the vertex is $\frac{-5}{2}$
Substitute $\frac{-5}{2}$ for x to find the y-coordinate of the vertex.
$y=-2(\frac{-5}{2})^2-10(\frac{-5}{2})$
$=\frac{25}{2}$
The vertex is $(\frac{-5}{2},\frac{25}{2})$
Find some other points for the graph.
$(-5,0)$
$(0,0)$
Graph the vertex and the points we found.
