What is ∑n=18(3n−1) equal to?
This is the sum of an arithmetic series
The first term is 3(1) - 1 = 2
The eighth term is 3(8) - 1 = 23
The sum is
[first term + eigth term] * number of terms / 2 =
[ 2 + 23 ] * 8 / 2 =
[25] * 4 =
100