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Find the square root of 126 + 10√5,1. 1 + 5√52. 1 - 5√5 3. 2 + √54. 2 - √5 |
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Answer» Correct Answer - Option 1 : 1 + 5√5 Given: 126 + 10√5 Formula used: (a + b)2 = a2 + b2 + 2ab Calculation: 10√5 = 2 × 1 × 5√5 Let a = 1 , b = 5√5 ⇒ (a + b)2 = a2 + b2 + 2ab ⇒ (1 + 5√5)2 = 1 + 125 + 2 × 1 × 5√5 ⇒ (1 + 5√5)2 = 126 + 10√5 ⇒ √(126 + 10√5) = √(1 + 5√5)2 ⇒ √(126 + 10√5) = 1 + 5√5 ∴ The square root of (126 + 10√5) is (1 + 5√5). |
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