$\begin{array}{1 1} 2x \tan^{-1}x- \log |1+x^2|+c \\ 2x \cos^{-1}x- \log |1+x^2|+c \\2x \cos^{-1}x+ \log |1+x^2|+c \\ 2x \cos^{-1}x- \log |1-x^2|+c \end{array} $