Question

Sigma Notation: Need Help!!

Problem 1:
Evaluate the summation of 3 times negative 2 to the n minus 1 power, from n equals 1 to 5.

Choices:
A.-93
B.-33
C.33
D.93,

Answer 1

3 x -2^(n-1)

To answer this question, first solve the equation 3 x -2^(n-1) for n=1, n=2,
n=3, n=4, and n=5.

Where n=1
3 x -2^(1-1)
3 x -2^0
3 x 1
n1 = 3


Where n=2
3 x -2^(2-1)
3 x -2^1
3 x -2
n2 = -6


Where n=3
3 x -2^(3-1)
3 x -2^2
3 x 4
n3 = 12


Where n=4
3 x -2^(4-1)
3 x -2^3
3 x -8
n4 = -24


Where n=5
3 x -2^(5-1)
3 x -2^4
3 x 16
n5 = 48


The next step is to find the summation by adding n1 + n2 + n3 + n4 + n5.

3 + (-6) + (12) + (-24) + (48) =
3 - 6 + 12 - 24 + 48
= 33
The answer is C. 33