Sketch the following graph. Indicate the axis of symmetry and the coordinate of the turning point on the graph.

$2x^2+4x=y$

Sketch the following graph. Indicate the axis of symmetry and the coordinate of the turning point on the graph.

$y=3-{(x+1)}^2$

Sketch the following graph. Indicate the axis of symmetry and the coordinate of the turning point on the graph.

$y=4-2{(x+3)}^2$

Sketch the following graph. Indicate the axis of symmetry and the coordinate of the turning point on the graph.

$y=17+6x-x^2$

Sketch the following graph. Indicate the axis of symmetry and the coordinate of the turning point on the graph.

$y=5-8x+2x^2$

Sketch the following graph. Indicate the axis of symmetry and the coordinate of the turning point on the graph.

Sketch the following graph. Indicate the axis of symmetry and the coordinate of the turning point on the graph.

$y=-{(x+2)}^2-1$

The equation for the curved supporting arch of a bridge (shown in red on the diagram) is given by $h=-\frac{1}{40}{\left(x-20\right)}^2$  where $h m$ is the distance below the base of the bridge and $x m$ is the distance from the left side.

Determine the turning point of the graph of the relationship.

The equation for the curved supporting arch of a bridge (shown in red on the diagram) is given by $h=-\frac{1}{40}{\left(x-20\right)}^2$  where $h m$ is the distance below the base of the bridge and $x m$ is the distance from the left side.

What are the possible values for $x$?