Which of the following function is even function
$f(x) = \frac{{{a^x} + 1}}{{{a^x} - 1}}$
$f(x) = x\left( {\frac{{{a^x} - 1}}{{{a^x} + 1}}} \right)$
$f(x) = \frac{{{a^x} - {a^{ - x}}}}{{{a^x} + {a^{ - x}}}}$
$f(x) = \sin x$
The range of the function $f(x) = \frac{x}{{1 + \left| x \right|}},\,x \in R,$ is
Greatest value of the function, $f(x) = - 1 + \frac{2}{{{2^x}^2 + 1}}$ is
The domain of the derivative of the function $f(x) = \left\{ \begin{array}{l}{\tan ^{ - 1}}x\;\;\;\;\;,\;|x|\; \le 1\\\frac{1}{2}(|x|\; - 1)\;,\;|x|\; > 1\end{array} \right.$ is
Range of the function $f(x) = {\sin ^2}({x^4}) + {\cos ^2}({x^4})$ is