CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2004

  • question_answer
    If \[\frac{\log x}{a-b}=\frac{\log y}{b-c}=\frac{\log z}{c-a}\], then \[xyz\] is equal to :

    A)  0                                            

    B)  1

    C)  -1                                          

    D)  2

    Correct Answer: B

    Solution :

    Given that, \[\frac{\log x}{a-b}=\frac{\log y}{b-c}=\frac{\log z}{c-a}\] Let each ratio be k and \[A=xyz\] then, \[\log x=k\,(a-b),\,\log \,y=k\,(b-c)\] and \[\log \,z=k\,(c-a)\] \[\therefore \]  \[\log \,A=\log \,x+\log \,y+\log \,z\]                 \[=k\,(a-b)+k\,(b-c)+k\,(c-a)\]                 \[=k\,[a-b+b-c+c-a]\]                 \[=k[0]\] \[\therefore \]  \[\log \,A=\log \,(xyz)=0\]           \[[\because \,A=xyz]\] \[\Rightarrow \]               \[xyz={{e}^{0}}\] \[\Rightarrow \]               \[xyz=1\]


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