If a and b are two positive real numbers such that 4a2 + b2 = 20 and ab = 4, then the value of 2a + b is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 6
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Understanding Tricks |
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Application 4a2 + b2 = 20 ⇒ (2a)2 + b2 = 20 and ab = 4 |
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Now ⇒ (2a + b)2 - 2.2ab = 20 ⇒ (2a + b)2 = 20 + 16 ⇒ (2a + b)2 = 36 ⇒ (2a + b) = 6 |