CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2007

  • question_answer
    The number of positive divisors of \[252\] is

    A)  \[9\]                                    

    B)  \[5\]

    C)  \[18\]                                  

    D)  \[10\]

    Correct Answer: C

    Solution :

    We know that, if \[a=p_{1}^{{{\alpha }_{1}}}.p_{2}^{{{\alpha }_{2}}}....\] Then, the total number of positive divisors of a is  \[T(a)=({{\alpha }_{1}}+1)\,({{\alpha }_{2}}+1).....\] Given,    \[252={{2}^{2}}\times {{3}^{2}}\times {{7}^{1}}\] Here,     \[{{\alpha }_{1}}=2,\,{{\alpha }_{2}}=2,{{\alpha }_{3}}=1\] \[\therefore \]  \[T(a)=(2+1)\,(2+1)(1+1)\]                 \[=3.3.2\]                 \[=18\]


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