When an electric current passes through two resistors with
resistance r and s , connected in parallel, the combined
resistance, R , can be calculated from the equation
{1 \over R} = {1 \over {r}} + {1 \over {s}},
where R , r , and s are positive.
Assume that s is constant.

Find

Is

(Enter **increasing**,
**decreasing**, **neither**, or
**both** (write both if there are values of

If we consider the interval

maximum:

minimum:

(Enter **none** if there is no global maximum or
minimum for this function.)

You can earn partial credit on this problem.