If $4x^2 + y^2 = 40$ and xy = 6, (x > 0, y > 0) then the value of 2x + y is

24 16 4 8

8

If $4x^2 + y^2 = 40$ xy = 6, (x > 0, y > 0) then the value of 2x + y = ? We know that, (a + b)2 = a2 + b2 + 2ab  (2x + y)2 = 4x2 + y2 +4xy xy = 6 (Given) 4xy = 4 × 6 = 24 Now, (2x + y)2 = 4x2 + y2 + 4xy Put the values of y2 + 4x2 and 4xy from above  (2x + y)2 = 40 + 24 = (2x + y)2  = 64 = (2x + y) = 8