Question

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

A) −93
B) −33
C) 33
D) 93

Answer 1

There is a shortcut way, but since you only have 5 to do, it isn't hard:

Answer 2

n(1) = 3(-2)^(1-1); n(1) = 3
n(2) = 3(-2)^(2-1); n(2) = -6
n(3) = 3(-2)^(3-1); n(3) = 12
n(4)= 3(-2)^(4-1); n(4) = -24
n(5) = 3(-2)^(5-1); n(5) = 48


3-6+12-24+48 = 33