QII{:[(d^(2)x)/(dt^(2))+6(dx)/(dt)+25 x=0],[" at "t=0=>x=0" \& "v=-12" bt isee "],["-ve sign be lebt "],[[(d^(2))/(dt^(2))+6(d)/(dt)+25]x=0],[D^(2)+6D+25=0],[0=(-6+-sqrt(36-100))/(2)],[D=-3+-4i=>alpha=-3","beta=4],[alpha+-i beta],[x=e^(alpha)[c_(1)cos beta t+c_(2)sin be ... See the full answer