Q45 / 125 · BITSAT 2014 · Mathematics

$2^{3 n}-7 n-1$ is divisible by

  • A
    64
  • B
    36
  • Correct answer
    C
    49
  • D
    25

Solution

$2^{3 n}-7 n-1 \quad$ Taking $n=2 ;$ $$ \begin{array}{l} 2^{6}-7 \times 2-1 \\ =64-15=49 \end{array} $$ Therefore this is divisible by 49 .

Hence, the correct answer is option: 'C'.

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