Multiple choice

Which of the following will not be a term of the sequence $11,20,29,.....$

  1. $326$
  2. $173$
  3. $388$

  4. none
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The sequence is an arithmetic progression with first term 11 and common difference 9. The general term is a_n = 11 + (n-1)9 = 9n + 2. Checking the options: 326 = 9n + 2 => 324 = 9n => n = 36. 173 = 9n + 2 => 171 = 9n => n = 19. 388 = 9n + 2 => 386 = 9n (not divisible).

AI explanation

The given sequence is an arithmetic progression with the first term a = 11 and a common difference d = 9, making its general formula T_n = 11 + (n - 1)9 which simplifies to 9n + 2. To check if a number belongs to this sequence, subtract 2 from the number and see if the result is divisible by 9. For the number 388, subtracting 2 gives 386, which is not perfectly divisible by 9 (since 9 * 42 = 378 and 9 * 43 = 387), meaning 388 will not be a term in the sequence.

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