Answer
See below
Work Step by Step
We know the following equation for an ellipse centered at the origin:
$$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$$
Where $(0,\pm a)$ is the vertex and $(\pm b,0)$ is the co-vertex.
Thus, we find:
$$\frac{x^2}{(\sqrt 49)^2}+\frac{y^2}{(9)^2}=1$$
$$\frac{x^2}{49}+\frac{y^2}{81}=1$$
