MCQ
The function $f (x) =$ $\mathop {Lim}\limits_{n \to \infty } \,\,\frac{{{x^{2n}} - 1}}{{{x^{2n}} + 1}}$ is identical with the function
  • A
    $g (x) = sgn(x - 1)$
  • B
    $h (x) = sgn (tan^{-1}x)$
  • $u (x) = sgn( | x | - 1)$
  • D
    $v (x) = sgn (cot^{-1}x)$

Answer

Correct option: C.
$u (x) = sgn( | x | - 1)$
c
$f (x) =$$\left[ \begin{gathered}   \hfill \\   \hfill \\   \hfill \\   \hfill \\ \end{gathered}  \right.$ $\begin{gathered}   - 1\,\,\,\,\,\,if\,\, - 1 < x < 1 \hfill \\   \hfill \\  \,\,\,0\,\,\,\,\,\,if\,\,x = 1\,\,or\,\, - 1 \hfill \\   \hfill \\  \,\,\,1\,\,\,\,\,\,if\,\,|x| > 1 \hfill \\ \end{gathered} $   and $g (x) = sgn(|x| - 1)$ is same 

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