$\"\"$

\

The revenue function is $\"\"$ .

\

(a).

\

At what price $\"\"$ ,the revenue is zero.

\

Therefore ball will strike the ground at distance $\"\"$

\

Substitute $\"\"$ in $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$ or $\"\"$ .

\

The revenue is zero where price $\"\"$ is $ $\"\"$ and $ $\"\"$ .

\

$\"\"$

\

(b).

\

The revenue is$ $\"\"$ .

\

Therefore substitute $\"\"$ in $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Find the vertex of above quadratic function $\"\"$ .

\

$\"\"$

\

Compare it to $\"\"$ .

\

$\"\"$ , $\"\"$ and $\"\"$ .

\

Since $\"\"$ , then the parabola open upward.

\

$\"\"$

\

$\"\"$

\

$\"\"$ coordinate of vertex is $\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Vertex $\"\"$ .

\

$\"\"$

\

Graph:

\

Graph the quadratic equation $\"\"$

\

Draw the coordinate plane.

\

Plot the intercepts and vertex.

\

Connect the plotted points.

\

$\"\"$

\

Observe the graph:

\

The price $\"\"$ is in between $ $\"\"$ and $ $\"\"$ .

\

Hence $\"\"$ .

\

$\"\"$

\

(a).The price $\"\"$ is $ $\"\"$ and $ $\"\"$ .

\

(b). $\"\"$ .