Y ' = (Cosx)' *(lnx+3) + Cosx * (lnx+3)' = - Sinx *(lnx+3) + Cosx * 1/x
y '' = (- Sinx * (lnx+3))' + (Cosx * 1/x)' = (-Sinx)' * (lnx+3) - Sinx * (lnx+3)' + (Cosx)' * 1/x + Cosx * (1/x)' = - Cosx * (lnx+3) - Sinx * 1/x - Sinx *1/x - Cosx * 1/x²=
= - Cosx(lnx+3+1/x²) - 2Sinx / x