微分方程<img src="/Image1/20/204ead39233a1494e3ee155796a2e9f9.png" />+<img src="/Image1/20/204ead39233a1494e3ee155796a2e9f9.png" />6′+9<img src="/Image1/20/204ead39233a1494e3ee155796a2e9f9.png" />＝0的通解为<img src="/Image1/20/204ead39233a1494e3ee155796a2e9f9.png" />＝（）。<br>A:（C1+C2<img src="/Image1/3d/3dd019a70475357568fcc53c3bff5343.png" />）e<img src="/Image1/36/36569bbbe378656b49431368f24d702f.png" /><br>B:（C1+C2<img src="/Image1/3d/3dd019a70475357568fcc53c3bff5343.png" />）e-<img src="/Image1/36/36569bbbe378656b49431368f24d702f.png" /><br>C:C1e<img src="/Image1/36/36569bbbe378656b49431368f24d702f.png" />+C2e-<img src="/Image1/36/36569bbbe378656b49431368f24d702f.png" /><br>D:C1cos3<img src="/Image1/3d/3dd019a70475357568fcc53c3bff5343.png" />+C2sin3<img src="/Image1/3d/3dd019a70475357568fcc53c3bff5343.png" />