Question

An arithmetic series consists of consecutive integers that are multiples are of 4. What is the sum of the first nine terms of this sequence if the first term is 0

Answer 1

144

Explanation:

If the first term is 0, the second is 4, the third 16, and so on. The appropriate formula for this is a(n) = 4*(n-1). The ninth term is a(9) = 4*(8) = 32

This partial series looks like {0, 4, 8, 12, 16, 20, 24, 28, 32 }

The sum of these nine terms is equal to 9 times {the sum of the 1st and last terms}, divided by 2, or 9(0+32)/2, or 9(16), or 144.