Two square terms ax^2 + by^2 with the coefficients "a" and "b" of the same sign (both "+" or both "-") ========>
the figure is an ellipse (if it is not empty).
Solution:
Circles have the coefficients of x^2 and y^2 identical in value and in sign (not the case here)
Hyperbolas have opposing signs between the coefficients of x^2 and y^2 (not the case here)
Ellipses have the coefficients have the same sign, but different values. (case here)
Note that in all cases, first degree terms may be present without changing the above. Also xy terms may be present in cases where the conic section is rotated from the x-y axes.