I have to find the general solution of

$\displaystyle d^2/dt^2\theta +(2\mu +K_D)d/dt\theta +\omega(\theta-\theta(0))$

could i just say

$\displaystyle 2\mu +K_D =Q$ and$\displaystyle \theta-\theta(0) =x$

then i get a normal SHM equation, solve it for under, critical and overdamping then sub them back in?