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If the sum of two numbers is 10 and the sum of their reciprocals is 5/12 then what will be the numbers?1. 7, 32. 9, 13. 8, 24. 6, 4 |
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Answer» Correct Answer - Option 4 : 6, 4 Given: Sum of two numbers = 10 Sum of their reciprocals = 5/12 Calculation: Let the numbers be x and y So, x + y = 10 ----(i) And, (1/x) + (1/y) = 5/12 ----(ii) ⇒ (x + y)/xy = 5/12 Now, ⇒ 10/xy = 5/12 ⇒ xy = 12 × 2 = 24 ----(iii) Now, (10 – y) × y = 24 ⇒ 10y – y2 = 24 ⇒ y2 – 10y + 24 = 0 ⇒ y2 – 6y – 4y + 24 = 0 ⇒ y(y – 6) – 4(y – 6) = 0 ⇒ (y – 6) (y – 4) = 0 ⇒ y = 6, 4 ∴ The required numbers are 6 and 4 |
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