ĐK: $x\in[-1;1] $
$\Leftrightarrow\frac{2x}{\sqrt{x+1}+\sqrt{1-x}}\geq x$$\Leftrightarrow x(\frac{2}{\sqrt{1+x}+\sqrt{1-x}}-1)\geqslant 0$
+) TH1: $\left\{ \begin{array}{l} x\geqslant 0\\ 2\geqslant \sqrt{x+1}+\sqrt{1-x} \end{array} \right.\Leftrightarrow \left\{ \begin{array}{l} x\geq 0\\ x^2\geq 0\end{array} \right.\rightarrow $ lđ
+) TH2: $\left\{ \begin{array}{l} x\leq 0\\ .......... \end{array} \right.$ xét tt