Obtain the solution of the differential equation:
1) 2x" + 7x' + 3x = 0, X(0) = 3, x'(0) = 0
2) x" + 3x' + 6x = 0, X(0) = 3, x'(0) = 0
3) ȳ + 4ȳ + 3y = 2r(t)
where the initial are y (0) = 0, ȳ (0) = 0 and r(t) = 1, t ≥ 0
4) d²f(t)/dt² + 5 df(t)/dt + 4f(t) = e⁻ᵗu(t)
assume that all the initial conditions are zero