Answer:
Option A:
Step-by-step explanation:
We are given with the series - 9 - 3 + 3 + 9 + . . . . + 81.
Note that the second term is obtained by adding 6 to the first term.
Each consecutive term is obtained by adding 6 to its previous term.
Therefore, we should be adding six two times to get the third term from the first term.
Putting it Mathematically, we get: - 9 + 6n
This gives all the terms of the sequence. Since, we have to add all the terms we take the summation.
Also, note that 81 is the 15 th term.
Therefore, - 9 - 3 + 3 + 9 + . . . . + 81 =
Hence, the answer.