JEE Main & Advanced Mathematics Applications of Derivatives Question Bank Increasing and Decreasing Function

  • question_answer
    If \[f(x)=\sin x-\frac{x}{2}\] is increasing function, then  [MP PET 1987]

    A)            \[0<x<\frac{\pi }{3}\]

    B)            \[-\frac{\pi }{3}<x<0\]

    C)            \[-\frac{\pi }{3}<x<\frac{\pi }{3}\]

    D)            \[x=\frac{\pi }{2}\]

    Correct Answer: C

    Solution :

               \[f(x)=\sin x-\frac{x}{2}\Rightarrow f'(x)=\cos x-\frac{1}{2}\]                    \[f'(x)>0\] for increasing function                    Obviously it is increasing for \[-\frac{\pi }{3}<x<\frac{\pi }{3}\].


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