Multiple choice

Find the wrong term of the series : $7, 9, 17, 42, 91, 172, 293$

  1. $91$
  2. $42$
  3. $17$
  4. $9$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The differences are: 9-7=2, 17-9=8, 42-17=25, 91-42=49, 172-91=81, 293-172=121. The pattern of squares is 1^2, 3^2, 5^2, 7^2, 9^2, 11^2. The difference 2 is wrong; it should be 1^2=1 (making the second term 8) or the first term should be different.

AI explanation

The differences between consecutive terms follow the pattern of squares of prime numbers. The differences required are 2^2 = 4, 3^2 = 9, 5^2 = 25, 7^2 = 49, 11^2 = 121, and 13^2 = 169. The second term should be 7 + 4 = 11, making 9 the wrong term in the series.

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