JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2010

  • question_answer
        If\[f\]and g are two increasing functions such that fog is denned, then

    A)  fog is an increasing function

    B)  fog is a decreasing function

    C)  fog is neither increasing nor decreasing

    D)  None of the above

    Correct Answer: A

    Solution :

                    Let\[{{x}_{1}},{{x}_{2}}\in R\]such that\[{{x}_{1}}<{{x}_{2}}\]. Then, \[{{x}_{1}}<{{x}_{2}}\] \[\Rightarrow \]               \[f({{x}_{1}})<f({{x}_{2}})\] (\[\because \]\[f\]is an increasing function) \[\Rightarrow \]               \[g\{f({{x}_{1}})\}<g\{f({{x}_{2}})\}\]  (\[\because \]is an increasing function) \[\Rightarrow \]               \[gof({{x}_{1}})<gof({{x}_{2}})\] Hence,\[gof\]is an increasing function.


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