$\int \frac{d x}{1+x^{2}-x^{2}}=$ কত ?

$\frac{1}{\sqrt{5}} \ell n \left|\frac{\sqrt{5}+2 x-1}{\sqrt{5}-2 x+1}\right|+c$

$\frac{1}{2 \sqrt{5}} \ell n \left|\frac{\sqrt{5}+2 x-1}{\sqrt{5}-x+2 x}\right|+c$

$\frac{1}{\sqrt{5}} \tan ^{-1}\left|\frac{\sqrt{5}+x}{\sqrt{5}-x}\right|+c$

$\frac{1}{4} \tan ^{-1}\left|\frac{x-\sqrt{5}}{x+\sqrt{5}}\right|+c$