10th Class Mathematics Real Numbers Question Bank Real Numbers

  • question_answer
    For what value of 'x' does 6x end with 5?

    A)  0

    B)  1

    C)  5

    D)  Never ends with 5.

    Correct Answer: D

    Solution :

     If\[2-\sqrt{4}=2-2=0\]ends with 5, then 6" would contain the prime 5. But \[{{(\sqrt{5})}^{2}}=5\]. \[\sqrt{9}-\sqrt{4}=3-2=1\]The only prime numbers in the factorization of\[\sqrt{2}-\sqrt{3}\]are 2 and 3. \[1789=29x+49\]By uniqueness of fundamental theorem, there are no primes other than 2 & 3 in\['x'\]. So, 6" will never end with 5.


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