Q1Long answerExercise 5.3
± 83 84 – 82 = = , 6 6 6 – 41 = 14, As n cannot be negative, so n = 14 Therefore, x = 3n – 2 = 3 × 14 – 2 = 40. Alternative solution: Here, 1, 4, 7, 10, ... x form an AP with a = 1, d = 3, S = 287 We have, S= 2a + ( n – 1) d So, 287 = 2 + ( n – 1) × 3 or, 574 = n (3n – 1) or, 3n 2 – n – 574 = 0 Now proceed as above.
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(A1) → (B 4) (A2) → (B 5) (A3) → (B 1) (A4) → (B 2) 5 3 11 10