I think there is a mistake in the equation √6(cos315+isin325)
where sin 325 should be sin 315, if so
1) the angle 315 is in the 4th quadrant, where cos is positive & sin, negative
cos 315 = cos(315-360) = -45 and cos(-45) = √2/2 & sin(-45) = - √2/2
Then z= √6(√2 / 2 - i√2 / 2)
z=√6 x √2 / 2 - √6 x √2 / 2) =√12 / 2 - i√12 / 2)
Simplify: z= √3 - i√3
