$8.(10$pts$)$ Use the figure below to answer the following questions.

$3\mathrm{.}1$ Sketch the root locus

$3\mathrm{.}2$ Mark the starting point and ending point of the root locus

$3\mathrm{.}3$ What's the value of the gain at the starting point of the root locus?

$3\mathrm{.}4$ What's the value of the gain at the ending point of the root locus?