\left\{-\text{A0} y'(t)+\text{a1} x''(t)+\text{b1} x'(t)+\text{c1} x(t)=\text{B0} e^{i \omega  t},\text{A0} x'(t)+\text{a2} y''(t)+\text{b2} y'(t)+\text{c2} y(t)=0\right\}