In this sequence, our common ratio is -3 (each value is -3 times the previous value). The first (or 1th) term of the sequence is 6, so we can form our equation:

Now we have to find the 11 term. To do so, we plug 11 into our equation where the x would be. Once that's done, we do the math as follows:
(plug in)
(simplify by subtracting 1 from 11 to get 10)
(simplify by calculating 3 to the power of 10 to get 59049)
(solve by multiplying 6 by 59040 to get 354294
Therefore, our 11th term in the sequence is 354394.