var('t a b')
@interact
def _(t_min=(-1,0), t_max=(1e-10,2), a=(0.01,5), b=(0,2)):
p1 = plot(exp(-a*t)*sin(2*pi*t),[t,t_min,t_max],color="blue",legend_label="$x(t)=e^{-at}\sin(2\pi t)$");
p2 = plot(b*sin(2*pi*t),[t,t_min,t_max],color="red",legend_label="$b\,\sin(2\pi t)$");
p3 = plot([diff(exp(-a*t)*sin(2*pi*t),t)],[t,t_min,t_max],color="green")
P = p1+p2
show(P)