# Math Help - Reflexive relation

1. ## Reflexive relation

Is x=-/+y reflexive? (x, y) exists in R, on a set of all real numbers.

Sorry, don't know how to put in the positive or negative symbol.

I'm thinking it is, but I don't know how to express it in a proof.

Thanks!

2. Originally Posted by SlapnutsGT
Is x=-/+y reflexive? (x, y) exists in R
Is this true $\forall x \in \mathbb{R}$: both of these pairs $(x,x)~\&~(x,-x)$ are in the relation?

3. Originally Posted by Plato
Is this true $\forall x \in \mathbb{R}$: both of these pairs $(x,x)~\&~(x,-x)$ are in the relation?
I would assume yes, because it exists in a set of all real numbers. Only info given is:
Determine whether the relation R on the set of all real numbers is reflexive, symmetric, antisymmetric, and/or transitive, where $(x, y) \in \mathbb{R}$ if and only if $x=\pm\,y$.

4. Originally Posted by SlapnutsGT
I would assume yes, because it exists in a set of all real numbers. Only info given is:
Determine whether the relation R on the set of all real numbers is reflexive, symmetric, antisymmetric, and/or transitive, where $(x, y) \in \mathbb{R}$ if and only if $x=\pm\,y$.
You missed my point. If the answer is yes then it is reflexive.

BTW: To get $\pm$ type $$\pm$$

5. Doh! I can be a knucklehead sometimes, kinda missed your point because I'm struggling to understand discrete math. Math without numbers is still a new concept to me! Thanks you for the help!