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The sum of the first term and the last term of an AP is 51. The second last term is 42. Find the second term.1. 92. 73. 84. 6 |
Answer» Correct Answer - Option 1 : 9 Given: The sum of the first term and the last term is 51. The second last term is 42. Formula: Nth term of an AP, Tn = a + (n - 1)d, where ‘a’ is the first term, ‘n’ is the total number of terms and ‘d’ is the common difference. Calculation: Let the first term is ‘a’ and common difference is ‘d’. From the question a + Tn = 51 ⇒ a + a + (n – 1)d = 51 ⇒ 2a + (n – 1)d = 51 -----(1) Second last term = 42 T(n- 1 ) = 42 ⇒ a + (n – 2)d = 42 ----(2) Subtracting equation (2) from (1) we get a + (n – 1)d – (n – 2)d = 9 ⇒ a + nd –d –nd + 2d = 9 ⇒ a + d = 9 Second term = a + d = 9 ∴ required answer is 9. |
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