Question

What is the sum of the first nine terms of this Sequence if the first term is 0?

Answer 1

The answer is B.

Explanation:

First you write out the first nine multiples of 4. Then you add them.

4 + 8 + 12 + 16 + 20 + 24 + 28 + 32 + 36 = 180

Answer 2

D. 160

Explanation:

The sum of the sequence 1, 2, 3, 4, ... , n is n(n + 1)/2.

Here, you have the sum of 4(1, 2, 3, 4, ... , n), so the sum is 4[n(n + 1)/2]

In this case, the first term is 0, so the last term is the 8th term of the sequence above, so n = 8

4[n(n + 1)/2)] =

= 4[8(9)/2]

= 4[72/2]

= 4(36)

= 144

The closest answer is D. 160