Answer
$y=-2cos(\pi x)$
Work Step by Step
1. Based on the given graph, we can initially identify that it resembles a graph of negative cosine.
2. We can determine the amplitude $|A|=2$, period $p=2$, passing $(0,-2)$.
3. Write a model as $y=-2cos(\omega x)$
4. We have $\frac{2\pi}{\omega}=2$, thus $\omega=\pi$
5. The equation is $y=-2cos(\pi x)$
