MCQ
$\int\limits_0^\infty $ $\frac{x}{{(1\,\, + \,\,x)\,\,(1\,\, + \,\,{x^2})}}$ $d x$ :
  • A
    $\frac{\pi }{4}$
  • B
    $\frac{\pi }{2}$
  • C
    is same as $\int\limits_0^\infty $ $\frac{x}{{(1\,\, + \,\,x)\,\,(1\,\, + \,\,{x^2})}}$
  • both $(A)$ and $(C)$

Answer

Correct option: D.
both $(A)$ and $(C)$
d
Put $x = 1/t$ and add the two integrals 

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