JEE Main & Advanced Sample Paper JEE Main - Mock Test - 22

  • question_answer
    The remainder when \[2{{7}^{40}}\] is divided by 12 is

    A) 3                     

    B)        7           

    C) 9                     

    D)        11

    Correct Answer: C

    Solution :

    \[2{{7}^{40}}={{3}^{120}}\] \[{{3}^{119}}=\,\,{{\left( 4-1 \right)}^{119}}{{=}^{119}}{{C}_{0}}{{4}^{119}}{{-}^{119}}{{C}_{1}}{{4}^{118}}\] \[{{+}^{119}}{{C}_{2}}{{4}^{117}}\,-\,\,119{{C}_{3}}{{4}^{116}}+......+(-1)\] \[\therefore \,\,\,\,{{3}^{119}}=4k-1\] \[\therefore \,\,\,{{3}^{120}}=\,\,12k\,-3=12\,(k-1)+9\] \[\therefore \] the required remainder is 9.


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