If 
and 
, then write 
.
Here,
and
B={(x,y):y=-x, xϵR
and 
}
and 
={(x, y):-x2 =1,xϵR}
={(x, y):x2 =-1,xϵR}
=ϕ (∵ there is no 
such that 
)
1
If and , then write .
Here, and
B={(x,y):y=-x, xϵR
and }
and
={(x, y):-x2 =1,xϵR}
={(x, y):x2 =-1,xϵR}
=ϕ (∵ there is no such that )