Compute
\[\frac{1}{2^{1990}} \sum_{n = 0}^{995} (-3)^n \binom{1990}{2n}.\]
Question:
Compute
\[\frac{1}{2^{1990}} \sum_{n = 0}^{995} (-3)^n \binom{1990}{2n}.\]
Answer:
Let's think step by step.

user
-\frac{1}{2}
Compute
\[\frac{1}{2^{1990}} \sum_{n = 0}^{995} (-3)^n \binom{1990}{2n}.\]
train