Answer
$\frac{x^2}{16}+\frac{y^2}{4}=1$
Work Step by Step
Step 1. Based on the given conditions, we have $a=\frac{8}{2}=4, b=\frac{4}{2}=2$.
The ellipse is centered at $(0,0)$ with a horizontal major axis.
Step 2. We can write the equation as $\frac{x^2}{16}+\frac{y^2}{4}=1$
