Let R1 and R2 be two relations defined on \[\mathbb{R}\] by
\[a \,R_{1} \,b \Leftrightarrow a b \geq 0\] and \[a \,R_{2} \,b \Leftrightarrow a \geq b\]
Then,
Solutions · 1
Official solution
\[a\,{R_1}\,b \Leftrightarrow ab \ge 0\]
So, definitely \[(a,a) \in {R_1}\] as \[{a^2} \ge 0\]
If \[(a,b) \in {R_1} \Rightarrow (b,a) \in {R_1}\]
But if \[(a,b) \in {R_1},(b,c) \in {R_1}\]
\[\Rightarrow\] Then (a,c) may or may not belong to R1
Consider a=−5,b=0,c=5 so (a,b) and \[(b,c) \in {R_1}\] but ac1isnotequivalencerelationa\,{R\_2}\,b \Leftrightarrow a \ge b\[
(a,a) \in {R\_2} \Rightarrow \[ so reflexive relation
If (a,b) \in {R\_2}\[ then (b,a) ( may or may not belong to R2
\]