J & K CET Engineering J and K - CET Engineering Solved Paper-2006

  • question_answer
    The length of the sub tangent at any point \[({{x}_{1}},\,{{y}_{1}})\] on the curve \[y={{a}^{x}},\]\[(a>0)\] is

    A)  \[2\,\,\log \,a\]        

    B)  \[1/\,\,\log \,a\]

    C)  \[\log \,a\]          

    D)  \[{{a}^{{{2}_{{{x}_{1}}}}}}\log \,a\]

    Correct Answer: B

    Solution :

    Given curve is \[y={{a}^{x}}\] \[\therefore \] \[\frac{dy}{dx}={{a}^{x}}\,\log \,a\] Now, length of sub tangent at any point \[({{x}_{1}},{{y}_{1}})\]is \[=\frac{y}{dy/dx}=\frac{{{a}^{{{x}_{1}}}}}{{{a}^{{{x}_{1}}}}\,\log \,a}\] \[=\frac{1}{\log \,a}\]


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