The equation x2a2+y2b2=1\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1a2x2+b2y2=1 with a>ba > ba>b represents an ellipse. Where are the foci located?
On the y-axis
On the x-axis
At the center
On the line y=xy=xy=x