微分方程y"-7y'+12y=0的通解是( )。A.y=Ce3xB.y=Ce4xC. 发布时间:2017-12-05 17:24 │ 来源:www.tikuol.com 题型:单项选择题 问题: 微分方程y"-7y'+12y=0的通解是( )。A.y=Ce3xB.y=Ce4xC.y=e3x(C1cos 4x+C2sin 4x)D.y=C1e3x+C2e4x
题型:单项选择题 —How long did you stay there? —_______. [ ]A. In half a month B. After half a month C. For half a month D. Half a month ago 查看答案