RAJASTHAN ­ PET Rajasthan PET Solved Paper-2005

  • question_answer
    If a, b, c are different positive numbers, then the value of\[(b+ca)(c+a-b)(a+b-c)\]\[-abc\]will be

    A)  positive          

    B)  negative

    C)  zero              

    D)  None of these

    Correct Answer: B

    Solution :

     Let\[x=b+c-a,y=c+a-b\]and\[z=a+b-c\] Since, a, b, c are different numbers. \[a=\frac{y+z}{2}>\sqrt{yz}\] \[b=\frac{x+z}{2}>\sqrt{xz}\] \[c=\frac{x+y}{2}>\sqrt{xy}\] \[\therefore \] \[abc>\sqrt{yz}.\sqrt{xz}.\sqrt{xy}\] \[\Rightarrow \] \[abc>xyz\] \[\Rightarrow \]\[(b+c-a)(c+a-b)(a+b-c)-abc<0\] \[\therefore \]The value of\[(b+c-a)(c+a-b)(a+b-c)\] \[-abc\] will be negative.


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