Answer: The correct option is (B) -10.368.
Step-by-step explanation: Given that a sequence is defined b the following :
[tex]a_1=6,~~~a_n=-1.2a_{n-1}.[/tex]
We are to find the 4-th term.
To find the fourth term, we need to start from finding the first term.
If n = 2, then the second term is given by
[tex]a_2=-1.2\times a_1=-1.2\times 6=-7.2.[/tex]
If n = 3, then the third term is given by
[tex]a_3=-1.2\times a_2=-1.2\times (-7.2)=8.64.[/tex]
If n = 4, then the fourth term is given by
[tex]a_4=-1.2\times a_3=-1.2\times 8.64=-10.368.[/tex]
Thus, the fourth term of the given sequence is -10.368.
Option (B) is CORRECT.