Q. If $f(x)=\sin ^{-1}\left(\frac{2 x}{1+x^2}\right)-2 \tan ^{-1} x$ and $g(x)=\sin ^{-1}\left(\frac{1-x^2}{1+x^2}\right)+4 \tan ^{-1} x$ then range of $( f ( x )- g ( x ))$ for $x \in(-\infty,-1]$, is
Inverse Trigonometric Functions
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