(a)
\The function is
over the interval
.
Apply derivative on each side with respect to
.

(b)
\Graph :
\Graph the function and its derivative.
\
(c)
\Find the critical numbers by applying derivative.
\
Equate its derivative to
.

Therefore the critical numbers are
and
.
(d)
\Consider the test intervals to find the interval of increasing and decreasing.
\Test intervals are
,
and
.
| Test interval | \Test value | \Sign of ![]() | \
Conclusion | \
![]() | \
![]() | \
\
| \
Decreasing | \
![]() | \
![]() | \
\
| \
Increasing | \
![]() | \
![]() | \
\
| \
Decreasing | \
The function
is increasing on the interval
.
is positive on the interval
.
The function
is decreasing on the intervals
and
.
is negative on the intervals
and
.
(a)
\
.
(b)
\
(c)
\Critical numbers are
and
.
(d)
\
is positive on the interval
.
is negative on the intervals
and
.