Draw the graphs of linear equations y=x and y=-x on the same cartesian plane. What do you observe ?

Explanation

Any point on the graph of y =x will have x and y co ordinates same. The line passes through the points (0,0) , (1,1) and (-1,-1).
Again any point on the graph of y =-x will have x and y co-odinates of opposite signs but with the same magnitude . The line pases through the points (1,-1), (-1,1) and (0,0).
The graph of linear equations y = and y = -x on the same cartesian plane is shown in the figure given below

We observe that the graph of these equations passes through (0,0) i.e the origin