Hi

The following question i am having trouble completing

The equation of motion of a mass on the end of a vertical spring is

(where y is the displacement of the mass from the static equilibirum position). Given that initially ( i.e at time t=0) the displacement (y) is 3 and the velocity (y') is 0, find the solution to the equation in the form .

This is what i have done:

what should i do next in order to get it in the form of .

P.S