InterviewSolution
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InterviewSolution
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If a2 + b2 = 2b + 4a – 5, then what is the value of 2(a + b)?1. 102. 123. 84. 6 |
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Answer» Correct Answer - Option 4 : 6 Given: a2 + b2 = 2b + 4a – 5 Concept used: If (x – a)2 + (y – b)2 = 0 Then x – a = 0, y – b = 0 Formula used: (x – y)2 = x2 + y2 – 2xy Calculations: a2 + b2 = 2b + 4a – 5 ⇒ a2 – 4a + b2 – 2b + 5 = 0 ⇒ a2 – 4a + 4 + b2 – 2b + 1 = 0 ⇒ (a – 2)2 + (b – 1)2 = 0 ⇒ a – 2 = 0 and b – 1 = 0 ⇒ a = 2 and b = 1 Thus 2(a + b) = 2(2 + 1) = 2 × 3 = 6 ∴ The value of 2(a + b) = 6. |
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