SSC Sample Paper Mock Test-20 SSC CGL Tear-II Paper-1

  • question_answer
    What is the LCM of\[{{a}^{3}}b-a{{b}^{3}},\]\[{{a}^{3}}{{b}^{2}}+{{a}^{2}}{{b}^{3}}\]and \[ab\,\,(a+b)?\]

    A)  \[{{a}^{2}}{{b}^{2}}\,\,({{a}^{2}}-{{b}^{2}})\]

    B)  \[ab\,\,({{a}^{2}}-{{b}^{2}})\]

    C)  \[{{a}^{2}}{{b}^{2}}+a{{b}^{3}}\]

    D)  \[{{a}^{3}}{{b}^{3}}\,\,({{a}^{2}}-{{b}^{2}})\]

    Correct Answer: A

    Solution :

    Here, \[{{a}^{3}}b-a{{b}^{3}}=ab\,\,({{a}^{2}}-{{b}^{2}})=ab\,\,(a-b)(a+b)\] \[{{a}^{3}}{{b}^{2}}+{{a}^{2}}{{b}^{3}}={{a}^{2}}{{b}^{2}}\,\,(a+b)\] and       \[ab\,\,(a+b)=ab\,\,(a+b)\] \[\therefore \] \[LCM\,\,[({{a}^{3}}b-a{{b}^{3}}),({{a}^{3}}{{b}^{2}}+{{a}^{2}}{{b}^{3}}),ab\,\,(a+b)]\]             \[={{a}^{2}}{{b}^{2}}(a+b)(a-b)={{a}^{2}}{{b}^{2}}({{a}^{2}}-{{b}^{2}})\]


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