(4x + 2y)2 = 64
Expand the left side of the equation.
(4x + 2y)(4x + 2y) = 64
16x2 + 16xy + 4y2 = 64
Divide both sides of the equation by 4
4x2 + 4xy + y2 = 16
Subtract 4xy from both sides of the equation.
4x2 + y2 = 16 - 4xy
Since xy = 2 we can substitute 2 in for xy
4x2 + y2 = 16 - 4(2)
Simplify the right side of the equation.
4x2 + y2 = 8