JEE Main & Advanced AIEEE Solved Paper-2013

  • question_answer
    If\[x,y,z\]are in A.P. and\[ta{{n}^{-1}}x,ta{{n}^{-1}}y\]and \[ta{{n}^{-1}}z\] are also in A.P., then :     AIEEE Solevd Paper-2013

    A) \[x=y=z\]                            

    B) \[2x=3y=6z\]

    C)        \[6x=3y=2z\]

    D)        \[6x=4y=3z\]

    Correct Answer: A

    Solution :

    \[2y=x+z\]                          ? (1) As \[ta{{n}^{-1}}x,\text{ }ta{{n}^{-1}}y,\text{ }ta{{n}^{-1}}z\] in AP \[\Rightarrow \]\[2\text{ }ta{{n}^{-1}}y=ta{{n}^{-1}}\frac{x+z}{1-xz}\] \[\frac{2y}{1-{{y}^{2}}}=\frac{x+z}{1-xz}\] \[\frac{x+z}{1-{{y}^{2}}}=\frac{x+z}{1-xz}\]                          ? by (1) \[(x+z)\left\{ \frac{1}{1-{{y}^{2}}}-\frac{1}{1-xz} \right\}=0\] \[x+z=0\text{ }or\text{ }1-xz=x-{{y}^{2}}\] \[{{y}^{2}}=xz\] \[\Rightarrow \] \[x,\text{ }y,\text{ }z\] in GP. As \[x,\text{ }y,\text{ }z\] AP & GP \[\Rightarrow \] \[x=y=z\]


You need to login to perform this action.
You will be redirected in 3 sec spinner