Show that the relation $R$ on $\mathbb{R}$ defined as $R = \{(a,b): a \leq b\}$, is reflexive, and transitive but not symmetric.ORProve that the function $f: N \longrightarrow N$, defined by $f(x)=x^2+x+1$ is one-one but not onto. Find inverse of $f: N \longrightarrow S$, where $S$ is range of $f$.