Given equation is x2 + 2(2)1/2 xy + 2y2 + 4x + 4(2)1/2 y + 1 = 0
Comparing it with general equation of second degree i.e.
ax2 + 2hxy + by2 + 2gx + 2fy + c = 0
we have a = 1, h = (2)1/2, b = 2, g = 2, f = 2(2)1/2 and c = 1.
It this equation represents pair of two straight parallel lines then,
h2 - ab = 0
So, (2) - (1)(2) = 0
So, the given lines represent straight parallel lines.
Now, the distance between them(d) is given by
d = 2 ((g2 - ac) / a(a + b))1/2 = 2 ((4 - 1)/(1)(1 + 2))1/2 = 2(1) = 2 units (Ans).........