The n-th term of a geometric sequence with initial value a and common ratio r is given by [tex]a_n=a_1r^{n-1}[/tex].
We have [tex]a_1=-2[/tex] and [tex]r=3[/tex] and [tex]n=12[/tex]
Substitute:
[tex]a_{12}=-2\cdot3^{12-1}=-2\cdot3^{11}=-2\cdot177147=-354294[/tex]