The nth term of any geometric sequence can be expressed as:
a(n)=ar^(n-1), a(n)=nth term, a=initial term, r=common ratio, n=term number...
We can easily see that the first term, a=-8
The common ratio is 4/-8=-2/4=1/-2=r=-1/2 so the rule is:
a(n)=-8(-1/2)^(n-1) so the tenth term is:
a(10)=-8(-1/2)^(10-1)
a(10)=-8(-1/2)^9
a(10)=1/64
