If set A and B are defined as:A=(x,y):y=1x,x≠0,x∈RB={(x,y):y=−x,x∈R}, then

For A∩B we have to look for common values of A and B For this, on comparing the values of y from y=1x and y=−x we have 1x=−x or x2=−1, which is not possible.  Hence A∩B=ϕ .