JEE Main 2024 (Online) 29th January Morning ShiftQuestion 1
Let $R$ be a relation on $\mathbb{Z}\times\mathbb{Z}$ defined by $(a,b)R(c,d)$ if and only if $ad-bc$ is divisible by $5$. Then $R$ is
Sets, Relations and Function
Solution
Reflexive: $ab-ba=0$. Symmetric: $ad-bc$ divisible by 5 $\Rightarrow cb-da$ too. Not transitive: $(1,0)R(0,0)$, $(0,0)R(0,1)$ but $1\cdot1-0=1$ not divisible by 5, so $(1,0)\not R(0,1)$. Option (B).