Question

Find an equation for the nth term of the sequence. -4, -16, -64, -256, ...

Answer 1

It would be

an = 4×4n + 1

Answer 2

Ok, so seems to be geometric
an=a1(r)^(n-1)

a1=first term
r=commonr atio
n=number of term
first term is -4
common ratio is -16/-4=4

so
a1=-4
r=4

$a_n=-4(4)^{n-1}$

D is the answer