10th Class Mathematics Related to Competitive Exam Question Bank Algebra

  • question_answer
    LCM of the polynomials \[{{x}^{3}}y-x{{y}^{3}},\]\[{{x}^{4}}-2{{x}^{2}}{{y}^{2}}+{{y}^{4}}\]and\[{{x}^{4}}-{{y}^{4}}\]

    A)  \[xy({{x}^{2}}-{{y}^{2}}){{(x+y)}^{2}}(x-y)\]

    B)  \[xy({{x}^{2}}+{{y}^{2}}){{(x-y)}^{2}}{{(x+y)}^{2}}\]     

    C)  \[xy({{x}^{2}}+{{y}^{2}}){{(x-y)}^{2}}(x+y)\]

    D) \[xy({{x}^{2}}+{{y}^{2}})(x-y)(x+y)\]

    Correct Answer: B

    Solution :

                                  \[{{x}^{3}}y-x{{y}^{3}}=xy(x-y)(x+y)\]                 \[{{x}^{4}}-2{{x}^{2}}{{y}^{2}}+{{y}^{4}}={{({{x}^{2}}-{{y}^{2}})}^{2}}\]                 \[={{(x-y)}^{2}}{{(x+y)}^{2}}\]                  \[{{x}^{4}}-{{y}^{4}}=(x-y)(x+y)({{x}^{2}}+{{y}^{2}})\] \[\therefore \]  \[L.C.M=xy{{(x-y)}^{2}}{{(x+y)}^{2}}({{x}^{2}}+{{y}^{2}})\]


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