Multiple choice general knowledge math & puzzles

Complete the series. 11,12,9

  1. -8

  2. -9

  3. 25

  4. 69

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The pattern involves alternating operations: 11+1=12, 12-3=9, 9-17=-8. The absolute differences (1, 3, 17) follow the pattern 2^n ± 1 with alternating signs. More simply, this can be modeled as a cubic sequence f(n) = -5/3n³ + 8n² - 56/3n + 22 for n=1,2,3,4, giving terms 11, 12, 9, -8.