The given function will even function if\({\bf{f}}\left( {{\bf{ - x}}} \right){\bf{ = f}}\left( {\bf{x}} \right)\). The given function will be odd if\({\bf{f}}\left( {{\bf{ - x}}} \right){\bf{ = - f}}\left( {\bf{x}} \right)\).
Replace x by –x for a given function to check for odd or even.
\(\begin{array}{c}f\left( { - x} \right) = \frac{{\left( { - x} \right)}}{{\left( { - x} \right) + 1}}\\f\left( { - x} \right) = \frac{{ - x}}{{1 - x}}\end{array}\)
Here,\(f\left( { - x} \right) \ne f\left( x \right)\)or\(f\left( { - x} \right) \ne - f\left( x \right)\)
Therefore, the given function is neither odd nor even.