If a − 1/a = √21, where a > 0, then (a² + 1/a²)(a + 1/a) is equal to :यदि a − 1/a = √21, जहाँ a > 0, तो (a² + 1/a²)(a + 1/a) का मान है :
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Correct answer: B. 115
Explanation
Squaring, a² + 1/a² − 2 = 21, so a² + 1/a² = 23. Then (a + 1/a)² = 23 + 2 = 25, and since a > 0, a + 1/a = 5. The value = 23 × 5 = 115.वर्ग करने पर a² + 1/a² − 2 = 21, अतः a² + 1/a² = 23। तब (a + 1/a)² = 23 + 2 = 25, और a > 0 होने से a + 1/a = 5। मान = 23 × 5 = 115।More Mathematics & Numerical Ability questions
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