2. Solved Papers
  3. RAJASTHAN ­ PET

RAJASTHAN ­ PET Rajasthan PET Solved Paper-2006

  • question_answer
    If\[a<0\]and function\[({{e}^{ax}}+{{e}^{-ax}})\]is monotonic decreasing, then

    A)  \[x>0\]            

    B)  \[x<0\]

    C)  \[x>1\]            

    D)  \[x<1\]

    Correct Answer: B

    Solution :

     Let \[f(x)={{e}^{ax}}+{{e}^{-ax}},a<0\] \[\because \] \[f(x)\]is monotonic decreasing function. \[\therefore \] \[f'(x)=a{{e}^{ax}}+{{e}^{-ax}},a<0\] \[\Rightarrow \] \[{{e}^{ax}}>{{e}^{-ax}}\] \[(\because a<0)\] \[\Rightarrow \] \[{{e}^{2ax}}>1\] \[\Rightarrow \] \[2ax>0\] \[\Rightarrow \] \[2x<0\] \[(\because a<0)\] \[\Rightarrow \] \[x<0\]


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