If x^2 + 4y^2 = 40, xy = 6, and x > 2y, then the value of x - 2y is :

If $x^2 + 4y^2 = 40$,

xy = 6, and x > 2y,

then the value of x - 2y is = ?

We know,

a² + b² = (a - b)² + 2ab

According to question,

x² + 4y² = (x - 2y)² + 4xy

= (x - 2y)² = 40 - 4(6)

= (x - 2y)² = (16

=  x - 2y = 4