Covered today: Systems of first order linear DEs with constant coefficients. Direction fields, trajectories, and phase portraits.

For next time: 7.5 - 1,2,3,4,8,16,24-27 (only a,b on 24-27). This will not be collected.

Maple code for direction fields:

with(DEtools);

DEplot({diff(x1(t),t) = x1(t) + x2(t), diff(x2(t),t) = 4*x1(t) + x2(t)}, {x1(t), x2(t)}, t=-10..10, x1=-5..5, x2=-5..5);