Multiple choice

Find the next term of the given series: $4, 9, 20, 43,...$

  1. $90$
  2. $84$
  3. $96$
  4. $95$
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A Correct answer
Explanation

The pattern follows the rule: next term = (previous term * 2) + 1. Specifically, 4*2+1=9, 9*2+2=20, 20*2+3=43. Following this, 43*2+4=90.

AI explanation

We evaluate the differences between consecutive terms of the series. The differences are 5, 11 and 23, and the differences of these differences are 6 and 12, which form a geometric progression. Multiplying 12 by 2 gives 24, which we add to 23 to get the next first-level difference of 47. Adding 47 to the final term of 43 gives 90 as the result.

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