$\"\"$

(a)

The concentration $\"\"$ in a blood stream after $\"\"$ hours of injection is $\"\"$ .

Horizontal Asymptote :

Horizontal asymptote is $\"\"$ .

$\"\"$

Thus, the horizontal asymptote is $\"\"$ .

$\"\"$

(b)

Draw a coordinate plane.

Graph the function $\"\"$ .

$\"\"$

(c)

Plot the point Where the concentration $\"\"$ is maximum.

$\"\"$

Observe the graph :

The concentration $\"\"$ is maximum at $\"\"$ hours.

$\"\"$

(a) The horizontal asymptote is $\"\"$ .

(b)

Graph of the function $\"\"$ :

$\"\"$