find a formula for the general term of the sequence, starting with 𝑛=1

Question

1/2, -1/4, 1/8, -1/16....

I initially thought the answer was = 1/(-2)^n but that it incorrect.

Answer 1

Clearly, it is in the form of a*(-1/2)^n. You already have that, except for adding the a.

So for n=1

1/2=a(-1/2)^1=-a/2

1/2=-a/2 means a=-1

So, it is a*(-1/2)^n= -1*(-1/2)^n