Let $\epsilon=0.0005$ and Let $R_e$ be the relation $\{(x,y)\in R^2:|x-y|<\epsilon\}$, $R_e$ could be interpreted as the relation approximately equal. $R_e$ is
(A) Reflexive
(B) Symmetric
(C) transitive
Choose the correct answer from the options given below:
Solution
Solution:
Given relation is:
$R_e=\{(x,y)\in R^2:|x-y|<\epsilon\}$
where,
$\epsilon=0.0005$
Now check each property.
Check reflexive:
A relation is reflexive if every element is related to itself.
For any real number $x$,
$|x-x|=0$
Since,
$0<\epsilon$
So,
$|x-x|<\epsilon$
Therefore, $(x,x)\in R_e$.
Hence, $R_e$ is reflexive.
So, statement (A) is true.
Check symmetric:
A relation is symmetric if $(x,y)\in R_e$ implies $(y,x)\in R_e$.
If,
$(x,y)\in R_e$
then,
$|x-y|<\epsilon$
But,
$|x-y|=|y-x|$
So,
$|y-x|<\epsilon$
Therefore, $(y,x)\in R_e$.
Hence, $R_e$ is symmetric.
So, statement (B) is true.
Check transitive:
A relation is transitive if $(x,y)\in R_e$ and $(y,z)\in R_e$ imply $(x,z)\in R_e$.
Let,
$x=0,\ y=0.0004,\ z=0.0008$
Now,
$|x-y|=|0-0.0004|=0.0004<0.0005$
So, $(x,y)\in R_e$.
Also,
$|y-z|=|0.0004-0.0008|=0.0004<0.0005$
So, $(y,z)\in R_e$.
But,
$|x-z|=|0-0.0008|=0.0008$
Since,
$0.0008>0.0005$
So, $(x,z)\notin R_e$.
Therefore, $R_e$ is not transitive.
So, statement (C) is false.
Hence, only (A) and (B) are true.