a)\(f\left(x\right)\) xác định:
\(\Leftrightarrow\left|x+1\right|=\left|x-1\right|\Leftrightarrow x^2+2x+1\ne x^2-2x+1\Leftrightarrow x\ne0\)
b)\(f\left(-x\right)=\frac{\left|-x+1\right|+\left|-x-1\right|}{\left|-x+1\right|-\left|-x-1\right|}=\frac{\left|x-1\right|+\left|x+1\right|}{\left|x-1\right|-\left|x+1\right|}=-f\left(x\right)\)