The geometric sequence is given by:
[tex]a_n=ar^{n-1}[/tex]
Where:
a = first term of the sequence
r = common ratio
therefore:
[tex]\begin{gathered} a_n=-2\cdot4^{n-1}^{} \\ n=5 \\ a_5=-2\cdot4^{5-1} \\ a_5=-2\cdot4^4 \\ a_5=-2\cdot256 \\ a_5=-512 \end{gathered}[/tex]
