Question

What is the 8th term of the geometric sequence 4, -20, 100

Answer 1

\[\LARGE q=\frac{-20}{4}=\frac{100}{-20}=-5\]
now you have:
\[\LARGE a_8=a_1\cdot q^{8-1}\]
\[\LARGE a_8=4\cdot (-5)^{7}\]... pretty much the same as your previous post. ;)