Determine the general solution y = y(t) for each homogeneous equation. Show the techniques you use to find out the roots of the characteristic equations.
A) y^6 + 4y^5 + 4y^4= 0
b) y^4 + 32 y'' + 256 y =0
c) y^3 - 7y'' - 7y' + y=0
d) y^4 - 2y^3 + 34y'' - 168y' + 720y= 0