Answer:
The second summation, counting from the top.
Step-by-step explanation:
Remember the relation:
[tex]a^{-n} = \frac{1}{a^n}[/tex]
The first summation is:
4*( (-1/2)^0 + (-1/2)^1 + (-1/2)^2 + (-1/2)^3)
4*( 1 - 1/2 + 1/4 - 1/8) = 2.5
Now let's analyze the options.
Let's look at option A, here we only have 2 to different powers, so we never can have a summation equal to 2.5, then we can discard that option.
Let's look at the next one (B), it will be equal to:
= (1/4)*( (-2)^4 + (-2)^3 + (-2)^2 + (-2)^1) =
= (1/4)*( 16 - 8 + 4 - 2) = 2.5
Then this summation is the one equivalent to the first one.
