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Railways Sample Paper RRB (Group D) Sample Test Paper-6

  • question_answer
    If a and b are two odd positive integers, by which of the following integers is \[({{a}^{4}}-\,{{b}^{4}})\] always divisible?

    A)  3                    

    B)  6

    C)  8                    

    D)  12

    Correct Answer: C

    Solution :

    [c] \[{{a}^{4}}-{{b}^{4}}=({{a}^{2}}+{{b}^{2}})\,\,(a+b)\,\,(a-b)\] \[\therefore \]Required number \[=(3+1)\,\,(3-\,1)=8\]


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