Indranil

I understood but I have a doubt here. 

When y = x, the line goes through the middle (0,0) in the right direction in the graph, then why does the line go through the middle (0,0) in the left direction in the graph, when y = -x? I mean both lines should be in the same direction either in the right direction or in the left direction because the two equations ( y = x and y = -x ) shows same values 0,0 ( if x = 0, y = 0) and 0,0 ( if x = 0, y = -0 = 0). I am confused here. Could you explain, please?

Could you tell me, sir, why two lines go through the middle points in the graphs? (one to the right side and the another to the left side) I am confused  

It would be very very useful if you provide a graph. Could you provide a graph please, sir?

Thanks a lot.

Could you draw the graph, please so I can understand the concept better?