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