The curve is
and inflection point is
.
Inflection point is a point of the curve where the curve changes from up to down or down to up.
\Substitute
in the curve equation.

Rewrite the curve.
\
Apply derivative on each side with respect to
.

Again apply derivative on each side with respect to
.

Find the values of
and
.
Inflection point is
.
Equate
to zero and substitute
in
.

and
.
and
.
Substitute
in equation (1).

Substitute
in equation (1).

Find the additional inflection points.
\
Substitute
and
in
.

No inflection point is obtained, so
and
are not consider.
Now substitute
and
in
.

Find the inflection points.
\Equate
to zero.

and 
and
.
Therefore the inflection points at
.
and
.
The curve is 
Substitute
and
in the above curve.

The obtained curve is
.
Substitute
in the above curve.

Substitute
in the above curve.

Substitute
in the above curve.

The inflection points are
,
and
.
Therefore the additional inflection points are
and
.
and
.
The additional inflection points are
and
.