Given that x, y satisfy x 2-y 2 = 2XY, find the value of X − y x + y

Given that x, y satisfy x 2-y 2 = 2XY, find the value of X − y x + y


∵ x2-y2 = 2XY, ∵ (x + y) 2 = x2 + Y2 + 2XY = 2x2, ∵ x2 − Y2 (x + y) 2 = x − YX + y = 2xy2x2 = YX, ∵ x2-y2 = 2XY, divide by XY to get XY YX = 2, sort out (YX) 2 + 2 (YX) - 1 = 0 ∵ YX = − 2 ± 222 = - 1 ± 2, ∵ x, y is a positive number, ∵ YX = 2-1