JEE Main & Advanced Sample Paper JEE Main - Mock Test - 18

  • question_answer
    The function \[f(x)=1+x\,(\sin x)\,[\cos x],\] \[0<x\le \frac{\pi }{2}\](where \[[.]\] is GLF.)

    A) is continuous on \[\left( 0,\frac{\pi }{2} \right)\]

    B) is strictly increasing in \[\left( 0,\frac{\pi }{2} \right)\]

    C) is strictly decreasing in \[\left( 0,\frac{\pi }{2} \right)\]

    D) has global maximum value 2       

    Correct Answer: A

    Solution :

    For \[0<x\le \frac{\pi }{2};\] \[[\cos \,\,x]=0\] Hence, \[f(x)=1\]for all \[\left( 0,\frac{\pi }{2} \right]\] Trivially \[f(x)\] is continuous on \[\left( 0,\frac{\pi }{2} \right)\] This function is neither strictly increasing nor strictly decreasing and its global maximum is 1.


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