If ${a_1},\;{a_2},\;{a_3}.......{a_n}$ are in $A.P.$, where ${a_i} > 0$ for all $i$, then the value of $\frac{1}{{\sqrt {{a_1}} + \sqrt {{a_2}} }} + \frac{1}{{\sqrt {{a_2}} + \sqrt {{a_3}} }} + $ $........ + \frac{1}{{\sqrt {{a_{n - 1}}}  + \sqrt {{a_n}} }} = $

  • [IIT 1982]
  • A

    $\frac{{n - 1}}{{\sqrt {{a_1}} + \sqrt {{a_n}} }}$

  • B

    $\frac{{n + 1}}{{\sqrt {{a_1}} + \sqrt {{a_n}} }}$

  • C

    $\frac{{n - 1}}{{\sqrt {{a_1}} - \sqrt {{a_n}} }}$

  • D

    $\frac{{n + 1}}{{\sqrt {{a_1}} - \sqrt {{a_n}} }}$

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