Answer
$y = -1+\frac{1}{2}cot~(2x-3\pi)$
We can see the graph below.
Work Step by Step
$y = -1+\frac{1}{2}cot~(2x-3\pi)$
When $x = 0$, then $y = -1+\frac{1}{2}cot~(-3\pi)$ (which is undefined)
When $x = \frac{\pi}{8}$, then $y = -1+\frac{1}{2}cot~(-\frac{11\pi}{4}) = -0.5$
When $x = \frac{\pi}{4}$, then $y = -1+\frac{1}{2}cot~(-\frac{5\pi}{2}) = -1$
When $x = \frac{3\pi}{8}$, then $y =-1+\frac{1}{2}cot~(-\frac{9\pi}{4}) = -1.5$
When $x = \frac{\pi}{2}$, then $y = -1+\frac{1}{2}cot~(-2\pi)$ (which is undefined)
We can see the graph below.