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10th Class Mathematics Real Numbers Question Bank MCQs - Real Numbers

  • question_answer
    If the LCM of 12 and 42 is \[10m+4,\] then the value of m is:

    A) 50

    B) 8

    C) \[1/5\]

    D) 1

    Correct Answer: B

    Solution :

    Sol.      [b] We have, \[12=2\times 2\times 3={{2}^{2}}\times 3,\]
    \[42=2\times 3\times 7\]
    \[\therefore \,\,\,\,\,\,\,\,LCM(12,42)={{2}^{2}}\times 3\times 7=84\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,10m+4=84\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,10m=84-4=80\,\,\,\,\,\,\Rightarrow \,m=\frac{80}{10}=8\]


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