let \(f:\mathbb{R}\rightarrow\mathbb{R}\) be defined by \(f(x)=\left{\begin{array}{rcl} x^2+1,&\mbox{if}&x\leq 0\\\frac{1}{2}(x+2),&\mbox{if}&x\geq 0\end{array}\right\), then \(f\) is
not continuous at \(x=0\)
not continuous on \(\mathbb{R}\)
—>> continuous on \(\mathbb{R}\)
continuous at \(x=0\)