CLAT Sample Paper CLAT Sample Paper-9

  • question_answer
    \[2{{a}^{2}}+2{{b}^{2}}+2{{c}^{2}}-2ab-2bc-2ca\] is equal to 

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

    B)  \[{{(a-b)}^{2}}+{{(b-c)}^{2}}-{{(c-a)}^{2}}\]

    C)  \[{{(a-b)}^{2}}-{{(b-c)}^{2}}-{{(c-a)}^{2}}\]

    D)  \[{{(a-b)}^{2}}+{{(b-c)}^{2}}+{{(c-a)}^{2}}\]

    Correct Answer: D

    Solution :

    \[2{{a}^{2}}+2{{b}^{2}}+2{{c}^{2}}-2ab-2bc-2ca\] \[=\,({{a}^{2}}-2ab+{{b}^{2}})\,+\,({{b}^{2}}-2bc+{{c}^{2}})+\,({{c}^{2}}-2ca+{{a}^{2}})\] \[={{(a-b)}^{2}}+{{(b-c)}^{2}}+{{(c-a)}^{2}}\]


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