JEE Main & Advanced Mathematics Sequence & Series Question Bank Relation between AP., GP. and HP.

  • question_answer
    If \[\log (x+z)+\log (x+z-2y)=2\log (x-z),\,\]  then\[x,\,y,\,z\] are in   [RPET 1999]

    A) H.P.

    B) G.P.

    C) A.P.

    D) None of these

    Correct Answer: A

    Solution :

    \[\log \,(x+z)+\log (x+z-2y)=2\log (x-z)\] \[\log (x+z)(x+z-2y)=\log {{(x-z)}^{2}}\] \[xz-xy-yz=-xz\]\[\Rightarrow 2xz=xy+yz\] Dividing by \[x\,y\,z,\] we get Þ \[\frac{2}{y}=\frac{1}{x}+\frac{1}{z}\] i.e., \[\frac{1}{x},\frac{1}{y},\frac{1}{z}\]are in A.P. Þ \[x,y,z\] are in H.P.


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