The equation is
,
,
.
and
are opposite signs.



Completing the squares by adding
and
.


Let
.
.
(a)
\If
.

Here
and
are opposite signs.
Therefore, the equation
represents a hyperbola.
(b)
\If
.



.
The graph of the above equation represents two intersecting lines through the point
with slope
.
(a) The equation
represents a hyperbola.
(b) The equation
represents two intersecting lines through the point
with slope
.