1. r=-3 or r=2
2. y(t)=1/(tt-t-6), domain is (-2,3)
3. y(t)=8exp(t-5)+2
4. y(t)=(2+t)exp(2t)
5. after ln(8/13)/ln(12/13), i.e., around 6.0656 minutes
6. -1 is stable, 0 is semistable, 1 is unstable