If $4x^2 + y^2 = 40$ and xy = 6, (x > 0, y > 0) then the value of 2x + y is
Answer & explanation
Correct answer: option 4
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