Watched MIT 18.03 - lecture 9

I skipped lectures 7,8 (watched 7 partially and had a brief look at 8 ) because during this first serious confrontation with differential equations I want to follow the route of MST209 ( OpenLearn version ).

In 18.03 lecture 9 Prof. Mattuck talks about differential equations of type $y'' + Ay' + By = 0$. They are of the 2nd order, have constant coefficients and are homogeneous. The procedure for solving them is surprisingly similar to solving second order recurrence equations. The DE has a characteristic equation $r^2 + Ar + B=0$. If both roots are real and distinct the general solution then looks like $y=c_1 \cdot e^{r_1x} + c_2 \cdot e^{r_2x}$. The other two cases ( i.e. a pair of complex conjugates, two real equal roots ) are discussed during the rest of the lecture.