Answer:
Hyperbola
Explanation:
![a,b \\eq 0](https://img.qammunity.org/2020/formulas/mathematics/middle-school/sdxsclxnnd2hhhhr2gjr6m0xgzclf2l0yr.png)
is an ellipse.
is a hyperbola.
is also a hyperbola.
is a circle if
.
Notice the signs between each squared term.
It was the same sign for ellipse and circle (no minus; only plus).
It was different for hyperbola (+ to - for both).