parallel
If you mean y = 2x and y = 2x-1 then they are parallel lines because they have the same slope.
They are parallel lines
They are parallel lines with a vertical separation of 1.
If you mean: y = 2x and 2y = -x+4 then they are positive and negative straight line equations
They are parallel lines.
They are straight lines.
They are parallel lines.
neither
If: 12 = 2y+x then y = -1/2x+6 So: y = 2x+4 and y = -1/2x+6 which means that they are perpendicular lines
parallel
y2x is an expression, which cannot be graphed because we don't know what it equals. y = 2x, y2 = x, and 2y (or y2) = x are all things that could actually be graphed.
The lines are parallel, but not the same.