149. Find the general solution of the equation $y^{\prime \prime}-4 y^{\prime}+13 y=0$.
Solution. Let's form the characteristic equation and find its roots: $k^{2}-4 k+13=0 ; k_{1}=2+3 i, k_{2}=2-3 i$.

Write down the general solution of the equation:

$$
y=e^{2 x}\left(C_{1} \cos 3 x+C_{2} \sin 3 x\right)
$$