A particle moves along the x-axis so that the time ts, its displacement xm from the origin satisfies the differential equation

Given that when t=0, the particle is at rest at the origin, find its displacement at time ts.

I'm struggling with this because i think it involves complex roots, which i haven't done before.i know the C. Function is

and from the equation i get

Im a bit stuck and where to go from here. Can i still use surds when its complex? ie then i can cancel the 2's with the denominator?