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How many terms are identical in the two APs 19, 21, 23, up to 110 terms and 19, 22, 25, 28, up to 75 terms?

Options

  1. A35
  2. B36
  3. C37
  4. D38

Correct answer

C. 37

Step-by-step solution

For the first AP: 19, 21, 23, First term a₁ = 19 , common difference d₁ = 2 , number of terms n₁ = 110 . Last term L₁ = a₁ + (n₁ - 1)d₁ = 19 + (110 - 1) 2 = 19 + 218 = 237 . For the second AP: 19, 22, 25, 28, First term a₂ = 19 , common difference d₂ = 3 , number of terms n₂ = 75 . Last term L₂ = a₂ + (n₂ - 1)d₂ = 19 + (75 - 1) 3 = 19 + 222 = 241 . The identical terms of both APs form a new AP. The first common term is a = 19 . The common difference of the new AP is D = LCM (d₁, d₂) = LCM (2, 3) = 6 . The last term

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