#### Answer

$y = -2+\frac{1}{2}~cos~\frac{\pi}{4}x$
We can see the graph below.

#### Work Step by Step

$y = -2+\frac{1}{2}~cos~\frac{\pi}{4}x$
When $x = 0$, then $y = -2+\frac{1}{2}~cos~0 = -1.5$
When $x = 2$, then $y = -2+\frac{1}{2}~cos~(\frac{\pi}{2}) = -2$
When $x = 4$, then $y = -2+\frac{1}{2}~cos~(\pi)= -2.5$
When $x = 6$, then $y = -2+\frac{1}{2}~cos~(\frac{3\pi}{2}) = -2$
When $x = 8$, then $y = -2+\frac{1}{2}~cos~(2\pi) = -1.5$
We can see the graph below.