6)
\Step 1:
\ The function is
.
Differentiate
on each side with respect to
.

Find the critical points.
\Since
is a polynomial it is continuous at all the point.
Thus, the critical points exist when
.
Equate
to zero.

,
and
.
The critical points are
,
and
.
Substitute
in
.

Substitute
in
.

Substitute
in
.

The critical points are
and
.
The test intervals are
,
,
and
.
| Interval | \Test Value | \Sign of ![]() | \
Conclusion | \
![]() | \
| \
\
| \
Decreasing | \
![]() | \
![]() | \
\
| \
Increasing | \
![]() | \
![]() | \
\
| \
Decreasing | \
![]() | \
![]() | \
\
| \
Increasing | \
The function is increasing on the intervals
and
.
The function is decreasing on the interval
and
.
Step 2:
\
.
Differentiate
on each side with respect to
.
Find the inflection points.
\Equate
to zero.

The inflection points are at
.
Substitute
in
.

Substitute
in
.

Inflection points are
and
.
The test intervals are
,
and
.
| \
Interval \ | \
Test Value | \Sign of ![]() | \
Concavity | \
![]() | \
| \
![]() | \
Up | \
![]() | \
| \
![]() | \
Down | \
![]() | \
![]() | \
![]() | \
\
Up \ | \
The graph is concave up on the interval
and
.
The graph is concave down on the interval
.
The inflection point is
.
Step 3:
\Graph the function
:
Graph :
\1). Draw a coordinate plane.
\2). Plot the inflection points and critical points.
\3). Connect the plotted points.
\Solution: \ \
\The function is increasing on the intervals
and
.
The function is decreasing on the intervals
and
. \ \
The graph is concave up on the interval
and
.
The graph is concave down on the interval
.
\ \
\Graph of the function
:
\
.