微分方程DE（2.2）

introduce how to solve separable equations

Separable Equations:

1 order equations with separable variable
written in the form: f(x)dx=g(y)dy (seperate the variables and intergration)

eg： y=q(x)

进行积分

H(y) = G(x) + c
Both are antiderivatives of p(y) = 1/h(y) and g(x)

a dy=b dx
等式两边直接积分
求解， … = … +c

词汇：
Strictly monotonic 严格单调
Critical point 临界点
Phase portrait 相位图
Phase line 相线
Autonomous de： dy/dt = f(y), function of y, not t

2010.1.7