Let $a, a r, a r^2, \ldots . . .$. be an infinite $G.P.$ If $\sum_{n=0}^{\infty} a^n=57$ and $\sum_{n=0}^{\infty} a^3 r^{3 n}=9747$, then $a+18 r$ is equal to :

  • [JEE MAIN 2024]
  • A

    $27$

  • B

    $46$

  • C

    $38$

  • D

    $31$

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