Indefinite Integration

$2\left[x \tan ^{-1} x-\log \sqrt{1+x^2}\right]+C$

$2 x \tan ^{-1} x+\log \sqrt{1+x^2}+C$

$x \tan ^{-1} x+\log \sqrt{1-x^2}+C$

$2\left[\tan ^{-1} x-\log \sqrt{1+x^2}\right]+C$