1.
If f:[2,2]Rf:[-2,2]\to\mathbb R defined by f(x)={1+cx1cxx2x<0x+3x+10x2f(x)=\begin{cases}\frac{\sqrt{1+cx}-\sqrt{1-cx}}{x}&-2\le x<0\\\frac{x+3}{x+1}&0\le x\le2\end{cases} is continuous on [2,2][-2,2], then cc is