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If a and b are two positive numbers such that $4a^2 + b^2 = 20$ and ab = 4, then the value of 2a + b is : |
80 8 6 5 |
6 |
$4a^2 + b^2 = 20$ ab = 4, then the value of 2a + b is= ? ( a + b )2 = a2 + b2 + 2ab ( 2a + b )2 = 4a2 + b2 + 4ab ( 2a + b )2 = 20+ 4(4) ( 2a + b )2 = 36 2a + b= 6 |
