\((1)\) 函数\(y{=}\sqrt{{-}\lg(1{+}x)}\)的定义域为______.
\((2)\)已知\(f(x)\)为偶函数,当\(x{\leqslant }0\) 时,\(f(x){=}e^{x{+}1}{+}x{+}1\),则曲线\(y{=}f(x)\)在\((1{,}1)\)处的切线方程为______.
\((3)\) 对于函数\(y{=}f(x)\),如果\(f(x_{0}){=}x_{0}\),我们就称实数\(x_{0}\)是函数\(f(x)\)的不动点\({.}\)设函数\(f(x){=}3{+}\log_{2}x\),则函数\(f(x)\)的不动点一共有______个\({.}\)
\((4)\) 关于函数\(f(x){=}\ln\dfrac{1{-}x}{1{+}x}\),有下列三个命题:
\({①}f(x)\)的定义域为\(({-∞}{,}{-}1){∪}(1{,}{+∞})\);
\({②}f(x)\)为奇函数;
\({③}f(x)\)在定义域上是增函数;
\({④}\)对任意\(x_{1}{,}x_{2}{∈}({-}1{,}1)\),都有\(f(x_{1}){+}f(x_{2}){=}f(\dfrac{x_{1}{+}x_{2}}{1{+}x_{1}x_{2}}){.}\)
其中真命题有______\((\)写出所有真命题的番号\()\)