1,ĐK $-3\leq x\leq 1$
Bình phương 2 vế
$\Rightarrow 4-2\sqrt{3-2x-x^{2}}=x^{2}+2x+1$
$\Rightarrow -2\sqrt{3-2x-x^{2}}=x^{2}+2x-3$
Bình phương 2 về
$\Rightarrow 4(3-2x-x^{2})=x^{4}+4x^{3}-2x^{2}-12x+9$
$\Rightarrow x^{4}+4x^{3}+2x^{2}-4x-3=0$
$\Rightarrow (x-1)(x+1)^{2}(x+3)=0$
$\Rightarrow x=\pm 1;-3$