JEE Main & Advanced Mathematics Applications of Derivatives Question Bank Self Evaluation Test - Application of Derivatives

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

    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 :

    [a] 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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