t(t²-3)=2
t³-3t-2=0
t³+t²-t²-3t-2=0
t²(t+1)-(t+1)(t+2)=0
(t+1)(t²-t-2)=0
(t+1)(t-2)(t+1)=0
t+1=0或t-2=0
t=-1或t=2