希腊字母不好输入，用x、y代替了
dp/dθ +3p = 2dp/dθ =-3p+ 2∫dp/(-3p+2) = ∫dθ-(1/3)ln|(-3p+2)| =θ +C'ln|(-3p+2)| =-3θ -3C'-3p+2 = C''e^(-3θ)p = (1/3) (2- C''e^(-3θ) )=2/3 +C.e^(-3θ)
微方程比较有难度的，这个平台是不容易得到回复
