Reflexive or Irreflexive

Question

Are the following relations reflexive or irreflexive

1. $R = \{ (x,y) : y = 2x\}$

2. $R = \{ (x,y) : x \text{ is a sibling of }y\}$

3. $R = \{ (x,y) : x = 3 + y\}$

I believe 1 is reflexive but I'm not sure why

I think 2 is irreflexive as a person cannot be their own sibling

as for 3 i am not sure

Answer 1

1. Is it $\{$ ALWAYS / NEVER / SOMETIMES $\}$ true that $x=2x$?

2. Is it $\{$ ALWAYS / NEVER / SOMETIMES $\}$ true that $x$ is a sibling of $x$?

3. Is it $\{$ ALWAYS / NEVER / SOMETIMES $\}$ true that $x=3+x$?

"always"="reflexive"

"never"="irreflexive"

"sometimes"="neither"