Answer
See graph and explanations.
Work Step by Step
Step 1. Graph the equation as shown in the figure.
Step 2. We can identify from the given equation that $a=5, b=2$; thus $c=\sqrt {5^2-2^2}=\sqrt {21}$
Step 3. As the center of the ellipse is at $(0,0)$ and the major axis is horizontal, the foci are $(\pm\sqrt {21},0)$ as shown in the figure.
