Answer
$2cis30^\circ$ and $2cis(-30^\circ)$ are conjugates (As proved in the step by step work)
Work Step by Step
$2cis30^\circ$ = $2(cos30^\circ + isin30^\circ)$
$2cis(-30^\circ)$
= $2[cos(-30^\circ) + isin(-30^\circ)]$
= $2(cos30^\circ - isin30^\circ)$ (since $cos(-\theta) = cos\theta$ and $sin(-\theta) = -sin\theta$)
Hence, $2cis30^\circ$ and $2cis(-30^\circ)$ are conjugates.
