Answer:
Circle
Step-by-step explanation:
The general equation of a conic section is in the form
:
Ax^2+Bx+
Cy^2+Dy+E=0
When A or C is 0, the equation is that of a parabola.
When A and C have the same value (including signs), the equation is that of a circle.
When A and C have the same sign, the equation is that of an ellipse
.
When A and C have different signs, the equation is that on a hyperbola.
In this case, x^2 + y^2 = 9, A and C have the same sign, which means the equation is that of a circle.
